Solid-state imaging element and solid-state imaging apparatus

ABSTRACT

A first solid-state imaging element according to an embodiment of the present disclosure includes a bottom-electrode; a top-electrode opposed to the bottom-electrode; a photoelectric conversion layer provided between the bottom-electrode and the top-electrode and including a first organic semiconductor material; and—an upper inter-layer provided between the top-electrode and the photoelectric conversion layer, and including a second organic semiconductor material having a halogen atom in a molecule at a concentration in a range from 0 volume % or more to less than 0.05 volume %.

TECHNICAL FIELD

The present disclosure relates to a solid-state imaging elementincluding a photoelectric conversion layer that uses an organicsemiconductor material, and a solid-state imaging apparatus includingthe solid-state imaging element.

BACKGROUND ART

In a solid-state imaging element including an organic semiconductormaterial, in general, a photoelectric conversion layer is formed bystacking or mixing of a p-type organic semiconductor and an n-typeorganic semiconductor. This allows for efficient charge generation andcharge transport.

In addition, for example, PTL 1 discloses an organic photoelectricconversion element including a carrier blocking layer (an electronblocking layer and a hole blocking layer) and a charge transport layer(an electron transport auxiliary layer and a hole transport auxiliarylayer), respectively, between a negative electrode and an organicphotoelectric conversion film and between a positive electrode and theorganic photoelectric conversion film. The negative electrode and thepositive electrode are opposed to each other with the organicphotoelectric conversion film interposed therebetween. This organicphotoelectric conversion element attempts to further enhance chargeextraction efficiency by provision of the charge blocking layer and thecharge transport layer.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2014-22525

SUMMARY OF THE INVENTION

Incidentally, a solid-state imaging element is requested to enhanceelectric characteristics. In addition, the solid-state imaging elementis requested to have excellent responsivity.

It is desirable to provide a solid-state imaging element and asolid-state imaging apparatus that make it possible to enhance theelectric characteristics. In addition, it is desirable to provide asolid-state imaging element and a sold-state imaging apparatus that makeit possible to enhance the responsivity.

A first solid-state imaging element according to an embodiment of thepresent disclosure includes: a bottom-electrode; a top-electrode opposedto the bottom-electrode; a photoelectric conversion layer providedbetween the bottom-electrode and the top-electrode and including a firstorganic semiconductor material; and an upper inter-layer providedbetween the top-electrode and the photoelectric conversion layer, andincluding a second organic semiconductor material having a halogen atomin a molecule at a concentration in a range from 0 volume % or more toless than 0.05 volume %.

A first solid-state imaging apparatus according to an embodiment of thepresent disclosure includes one or a plurality of first solid-stateimaging elements according to the foregoing embodiment of the presentdisclosure, for each of a plurality of pixels.

In the first solid-state imaging element and the first solid-stateimaging apparatus according to the respective embodiments of the presentdisclosure, the upper inter-layer including the second organicsemiconductor material having a halogen atom in a molecule at aconcentration in a range from 0 volume % or more to less than 0.05volume % is provided between the top-electrode and the photoelectricconversion layer including the first organic semiconductor material.This makes it possible to suppress modification of organic materialsincluded in the top-electrode and the solid-state imaging element duringfilm formation.

A second solid-state imaging element according to an embodiment of thepresent disclosure includes: a bottom-electrode; a top-electrode opposedto the bottom-electrode; a photoelectric conversion layer providedbetween the bottom-electrode and the top-electrode and including anorganic semiconductor material that has one or two or more halogen atomsin a molecule and in which binding energy of a halogen atom havingsmallest binding energy in the molecule is 5.4 eV or higher; and anupper inter-layer provided between the top-electrode and thephotoelectric conversion layer.

A second solid-state imaging apparatus according to an embodiment of thepresent disclosure includes one or a plurality of second solid-stateimaging elements according to the foregoing embodiment of the presentdisclosure for each of a plurality of pixels.

In the second solid-state imaging element and the second solid-stateimaging apparatus according to the respective embodiments of the presentdisclosure, the upper inter-layer is provided between the top-electrodeand the photoelectric conversion layer, and the organic semiconductormaterial that has one or two or more halogen atoms in a molecule and inwhich binding energy of a halogen atom having smallest binding energy inthe molecule is 5.4 eV or higher is used as a material of thephotoelectric conversion layer. This makes it possible to suppress themodification of organic materials included in the top-electrode and thesolid-state imaging element during film formation.

A third solid-state imaging element according to an embodiment of thepresent disclosure includes: a bottom-electrode; a top-electrode opposedto the bottom-electrode; a photoelectric conversion layer providedbetween the bottom-electrode and the top-electrode and including anorganic semiconductor material having a halogen atom in a molecule; andan organic semiconductor layer provided between the top-electrode andthe photoelectric conversion layer, in which a distance between thetop-electrode and the photoelectric conversion layer is in a range from5 nm to 20 nm both inclusive.

A third solid-state imaging apparatus according to an embodiment of thepresent disclosure includes one or a plurality of third solid-stateimaging elements according to the foregoing embodiment of the presentdisclosure for each of a plurality of pixels.

In the third solid-state imaging element and the third solid-stateimaging apparatus according to the respective embodiments of the presentdisclosure, the organic semiconductor material is provided between thetop-electrode and the photoelectric conversion layer, and the distancebetween the top-electrode and the photoelectric conversion layer is inthe range from 5 nm to 20 nm both inclusive. This makes it possible tosuppress the modification of the top-electrode during film formation.

A fourth solid-state imaging element according to an embodiment of thepresent disclosure includes: a first electrode; a second electrodeopposed to the first electrode; and a photoelectric conversion layerprovided between the first electrode and the second electrode, in whichthe photoelectric conversion layer includes an exciton generation layerincluding a dye material and a first semiconductor material, and anexciton disassociation layer including a second semiconductor material.

A fourth solid-state imaging apparatus according to the embodiment ofthe present disclosure includes one or a plurality of fourth solid-stateimaging elements according to the foregoing embodiment of the presentdisclosure, for each of a plurality of pixels.

In the fourth solid-state imaging element and the fourth solid-stateimaging apparatus according to the respective embodiments of the presentdisclosure, the photoelectric conversion layer includes the excitongeneration layer including the dye material and the first semiconductormaterial, and the exciton disassociation layer including the secondsemiconductor material. This makes it possible to separate a lightabsorbing field (an exciton generation layer) and a charge generatingfield (an exciton disassociation layer).

According to the first solid-state imaging element and the firstsolid-state imaging apparatus according to the respective embodiments ofthe present disclosure, the upper inter-layer including the secondorganic semiconductor material having a halogen atom in a molecule at aconcentration in a range from 0 volume % or more to less than 0.05volume % is provided between the top-electrode and the photoelectricconversion layer including the first organic semiconductor material.This suppresses the modification during the film formation of theorganic materials included in the top-electrode and the solid-stateimaging element, thus making it possible to enhance electriccharacteristics.

According to the second solid-state imaging element and the secondsolid-state imaging apparatus according to the respective embodiments ofthe present disclosure, the upper inter-layer is provided between thetop-electrode and the photoelectric conversion layer, and the organicsemiconductor material that has one or two or more halogen atoms in amolecule and in which binding energy of a halogen atom having smallestbinding energy in the molecule is 5.4 eV or higher is used as thematerial of the photoelectric conversion layer. This suppresses themodification during the film formation of the organic materials includedin the top-electrode and the solid-state imaging element, thus making itpossible to enhance electric characteristics.

According to the third solid-state imaging element and the thirdsolid-state imaging apparatus according to the respective embodiments ofthe present disclosure, the organic semiconductor material is providedbetween the top-electrode and the photoelectric conversion layer tocause the distance between the top-electrode and the photoelectricconversion layer to be in the range from 5 nm to 20 nm. This suppressesthe modification of the top-electrode during the film formation, thusmaking it possible to enhance electric characteristics.

According to the fourth solid-state imaging element and the fourthsolid-state imaging apparatus according to the respective embodiments ofthe present disclosure, provision of the exciton generation layerincluding the dye material and the first semiconductor material and theexciton disassociation layer including the second semiconductor materialseparates the light absorbing field and the charge generating field.This makes it possible to enhance electric characteristics.

It is to be noted that effects described here are not necessarilylimited and any of effects described in the present disclosure may beincluded.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a cross-sectional configuration of anorganic photoelectric converter according to a first embodiment of thepresent disclosure.

FIG. 2 is a cross-sectional view of a schematic configuration of asolid-state imaging element according to the first embodiment of thepresent disclosure.

FIG. 3A is a diagram illustrating an example of an energy level of theorganic photoelectric converter illustrated in FIG. 1.

FIG. 3B is a diagram illustrating another example of the energy level ofthe organic photoelectric converter illustrated in FIG. 1.

FIG. 4 is a schematic plan view of a configuration of a pixel of asolid-state imaging apparatus illustrated in FIG. 2.

FIG. 5 is a cross-sectional view for description of a method ofmanufacturing the solid-state imaging element illustrated in FIG. 2.

FIG. 6 is a cross-sectional view of a process following FIG. 5.

FIG. 7 is cross-sectional view of a process following FIG. 6.

FIG. 8 is a cross-sectional view of a process following FIG. 7.

FIG. 9 is a schematic view of a cross-sectional configuration of anorganic photoelectric converter according to a second embodiment of thepresent disclosure.

FIG. 10 is a schematic view of a cross-sectional configuration of anorganic photoelectric converter according to a third embodiment of thepresent disclosure.

FIG. 11 is a schematic view of a cross-sectional configuration of anorganic photoelectric converter according to a fourth embodiment of thepresent disclosure.

FIG. 12A is a diagram illustrating an example of an energy level ofrespective layers that configure the photoelectric conversion layerillustrated in FIG. 11.

FIG. 12B is a diagram illustrating another example of the energy levelof the respective layers that configure the photoelectric conversionlayer illustrated in FIG. 11.

FIG. 13A is a diagram of another example of the energy level of therespective layers that configure the photoelectric conversion layerillustrated in FIG. 11.

FIG. 13B is a diagram illustrating another example of the energy levelof the respective layers that configure the photoelectric conversionlayer illustrated in FIG. 11.

FIG. 14 is a cross-sectional view of an example of a schematicconfiguration of a solid-state imaging element (an organic photoelectricconverter) according to a fifth embodiment of the present disclosure.

FIG. 15 is a cross-sectional view of an example of a schematicconfiguration of a solid-state imaging element (an organic photoelectricconverter) according to a sixth embodiment of the present disclosure.

FIG. 16 is a functional block diagram illustrating a solid-state imagingapparatus that uses, as a pixel, the solid-state imaging elementillustrated in FIG. 2.

FIG. 17 is a block diagram illustrating a schematic configuration of anelectronic apparatus that uses the solid-state imaging apparatusillustrated in FIG. 16.

FIG. 18 is a block diagram depicting an example of a schematicconfiguration of an in-vivo information acquisition system.

FIG. 19 is a view depicting an example of a schematic configuration ofan endoscopic surgery system.

FIG. 20 is a block diagram depicting an example of a functionalconfiguration of a camera head and a camera control unit (CCU).

FIG. 21 is a block diagram depicting an example of schematicconfiguration of a vehicle control system.

FIG. 22 is a diagram of assistance in explaining an example of aninstallation position of an imaging section.

FIG. 23 is a characteristic diagram illustrating a relation of a dopingconcentration and a rate of increasing a dark current from before toafter formation of a protective layer in Experiment 1.

FIG. 24 is a characteristic diagram illustrating the relation of thedoping concentration and the rate of increasing the dark current frombefore to after the formation of the protective layer in Experiment 2.

FIG. 25 is a characteristic diagram illustrating the relation of thedoping concentration and the rate of increasing the dark current frombefore to after the formation of the protective layer in Experiment 3.

FIG. 26 is a characteristic diagram illustrating a relation of minimumbinding energy and the rate of increasing the dark current from beforeto after the formation of the protective layer.

FIG. 27 is a characteristic diagram illustrating a relation of electronaffinity and a dark current of an upper inter-layer in experimentalexamples 28 to 33.

FIG. 28 is a characteristic diagram illustrating a relation of theelectron affinity and quantum efficiency of the upper inter-layer in theexperimental examples 28 to 33.

FIG. 29 is a characteristic diagram illustrating the relation of theelectron affinity and the dark current of the upper inter-layer inexperimental examples 34 to 37.

FIG. 30 is a characteristic diagram illustrating the relation of theelectron affinity and the quantum efficiency of the upper inter-layer inthe experimental examples 34 to 37.

FIG. 31 is a characteristic diagram illustrating a relation of adistance between a photoelectric conversion layer and a top-electrodeand a rate (J_(dk)-J_(dk,0))/J_(dk,0) of increasing the dark currentfrom before to after the formation of the protective layer.

MODES FOR CARRYING OUT THE INVENTION

In the following, some embodiments of the disclosure are described indetail with reference to the drawings. The embodiments described beloweach illustrate a specific example of the present disclosure, and thepresent disclosure is not limited to the following embodiments.Moreover, the present disclosure is not limited to positions,dimensions, dimension ratios, and other factors of respective componentsillustrated in the drawings. It is to be noted that description is givenin the following order.

-   1. First Embodiment (First example in which an upper inter-layer is    provided between a top-electrode and a photoelectric conversion    layer)-   1-1. Configuration of Solid-state Imaging Element-   1-2. Method of Manufacturing Solid-state Imaging Element-   1-3. Workings and Effects-   2. Second Embodiment (Second example in which the upper inter-layer    is provided between the top-electrode and the photoelectric    conversion layer)-   3. Third Embodiment (Third example in which the upper inter-layer is    provided between the top-electrode and the photoelectric conversion    layer)-   4. Fourth Embodiment (Example having a photoelectric conversion    layer including an exciton generation layer and an exciton    disassociation layer)-   4-1. Configuration of Organic Photoelectric Converter-   4-2. Workings and Effects-   5. Fifth Embodiment (Example in which an inter-layer is provided    between the exciton generation layer and the exciton disassociation    layer)-   6. Sixth Embodiment (Example in which another inter-layer is further    provided between the exciton generation layer and the exciton    disassociation layer)-   7. Application Examples-   8. Examples

1. FIRST EMBODIMENT

FIG. 1 schematically illustrates a cross-sectional configuration of anorganic photoelectric converter 20 included in a solid-state imagingelement (a solid-state imaging element 10) according to a firstembodiment of the present disclosure. FIG. 2 illustrates across-sectional configuration of the solid-state imaging element 10including the organic photoelectronic converter 20 illustrated in FIG.I. The solid-state imaging element 10 configures one pixel (a unit pixelP) in a solid-state imaging apparatus (a solid-state imaging apparatus1: see FIG. 14) such as a CMOS image sensor used in an electronicapparatus such as a digital still camera and a video camera, forexample.

(1-1. Configuration of Solid-State Imaging Element)

The solid-state imaging element 10 is of a so-called longitudinaldirection spectral type in which, for example, at least an organicphotoelectric converter 20A and two inorganic photoelectric converters32B and 32R are stacked in a longitudinal direction. The organicphotoelectric converter 20A is provided on a side on which a firstsurface (back side) 30A is located of a semiconductor substrate 30. Theinorganic photoelectric converters 32B and 32R are formed to be embeddedin the semiconductor substrate 30, and are stacked in a thicknessdirection of the semiconductor substrate 30. The organic photoelectricconverter 20A has a configuration in which a lower inter-layer 22 isprovided between a bottom-electrode 21 and a photoelectric conversionlayer 23A, and an upper inter-layer 24 is provided between thephotoelectric conversion layer 23A and a top-electrode 25.

The organic photoelectric converter 20A and the inorganic photoelectricconverters 32B and 32R selectively detect light of mutually differentwavelength ranges to perform photoelectric conversion. For example, theorganic photoelectric converter 20A acquires a green (G) color signal.The inorganic photoelectric converters 32B and 32R respectively acquirea blue (B) color signal and a red (R) color signal by a difference inabsorption coefficients. This allows the solid-state imaging element 10to acquire a plurality of types of the color signals in one pixelwithout using a color filter.

It is to be noted that in the present embodiment, description is givenof a case where electrons of electron-hole pairs generated byphotoelectric conversion in the inorganic photoelectric converters 32Band 32R are read as signal charges (in a case where an n-typesemiconductor region serves as a photoelectric conversion layer).Moreover, in the drawings, “+ (plus)” attached to “p” or “n” indicatesthat p-type or n-type impurity concentration is high, and “++” indicatesthat p-type or n-type impurity concentration is higher than that in acase of “+”.

For example, floating diffusions (floating diffusion layers) FD1, FD2,and FD3, a vertical type transistor (transfer transistor) Tr1, atransfer transistor Tr2, an amplifier transistor (modulation element)AMP, a reset transistor RST, and multilayer wiring 40 are provided on asecond surface (front side) 30B of the semiconductor substrate 30. Themultilayer wiring 40 has a configuration in which wiring layers 41, 42,and 43 are stacked in an insulating layer 44.

It is to be noted that in the drawings, the side on which the firstsurface 30A is located of the semiconductor substrate 30 is representedas a light entering side S1 and a side on which the second surface 30Bis located of the semiconductor substrate 30 is represented as a wiringlayer side S2.

The organic photoelectric converter 20A has a configuration in which, asdescribed above, the bottom-electrode 21, the lower inter-layer 22, thephotoelectric conversion layer 23A, the upper inter-layer 24, and thetop-electrode 25 are stacked in this order from the side on which thefirst surface 30A is located of the semiconductor substrate 30. In thepresent embodiment, the top-electrode 25 is separately formed for eachof the solid-state imaging elements 10, for example. Thebottom-electrode 21, the lower inter-layer 22, the photoelectricconversion layer 23A and the upper inter-layer 24 are provided as acontinuous layer common to a plurality of solid-state imaging elements10. For example, a layer having fixed charges (a fixed charge layer) 26,a dielectric layer 27 having an insulating property, and an inter-layerinsulating layer 28 are provided between the first surface 30A of thesemiconductor substrate 30 and the bottom-electrode 21. A protectivelayer 29 is provided on the top-electrode 25. Optical members such as aplanarization layer and an on-chip lens (both not illustrated) aredisposed above the protective layer 29,

A through electrode 34 is provided between the first surface 30A and thesecond surface 30B of the semiconductor substrate 30. The organicphotoelectric converter 20A is coupled to a gate Gamp of the amplifiertransistor AMP and the floating diffusion FD3 via the through electrode34. This allows the solid-state imaging element 10 to well transfer thecharges generated in the organic photoelectric converter 20A on the sideon which the first surface 30A is located of the semiconductor substrate30 to the side on which the second surface 30B is located of thesemiconductor substrate 30 via the through electrode 34, therebyenhancing characteristics.

The through electrode 34 is provided in each of the organicphotoelectric converters 20A in each of the solid-state imaging elements10, for example. The through electrode 34 has a function as a connectorbetween the organic photoelectric converter 20A and both the gate Gampof the amplifier transistor AMP and the floating diffusion FD3, andserves as a transmission path of the charges (herein, electrons)generated in the organic photoelectric converter 20A. A lower end of thethrough electrode 34 is coupled to a connection unit 41A in the wiringlayer 41 of the multilayer wiring 40 via a first lower contact 35, forexample. The connection unit 41A and the gate Gamp of the amplifiertransistor AMP are coupled via a second lower contact 45. The connectionunit 41A and the floating diffusion FD3 are coupled by a third lowercontact 46. A top edge of the through electrode 34 is coupled to thetop-electrode 25 via an upper contact 36, for example.

It is preferable that a reset gate Grst of the reset transistor RST bedisposed next to the floating diffusion FD3, as illustrated in FIG. 2.This makes it possible to reset the charges accumulated in the floatingdiffusion FD3 by the reset transistor RST.

The through electrode 34 penetrates the semiconductor substrate 30 andis separated from the semiconductor substrate 30 by a separation groove50, for example. It is preferable that, for example, the throughelectrode 34 include the same semiconductor as the semiconductorsubstrate 30, for example, silicon (Si), and have a resistance valuereduced by injection of the n-type or the p-type impurity (indicated byp+in FIG. 2, for example). It is also preferable that ahigh-concentration impurity region (indicated by p++ in FIG. 2, forexample) be provided in an upper end section a lower end section of thethrough electrode 34 and that connection resistance with the uppercontact 36 and the connection resistance with the first lower contact 35be further reduced. The through electrode 34 may include metal or aconductive material. Use of the metal or the conductive material makesit possible to further reduce the resistance value of the throughelectrode 34 and further reduce the connection resistance of the throughelectrode 34 with the first lower contact 35, the second lower contact45, and the third lower contact 46. As the metal or the conductivematerial included in the through electrode 34, aluminum (Al), tungsten(W), titanium (Ti), cobalt (Co), hafnium (Hf), tantalum (Ta), etc. areadopted.

00371 As illustrated in FIG. 2, an outer surface 51, an inner surface52, and a bottom surface 53 of the separation groove 50 are covered bythe dielectric layer 27 having an insulating property, for example. Thedielectric layer 27 has an outer dielectric layer 27A covering the outersurface 51 of the separation groove 50 and an inner dielectric layer 27Bcovering the inner surface 52 of the separation groove 50. It ispreferable that a cavity 54 be provided between the outer dielectriclayer 27A and the inner dielectric layer 27B. That is, the separationgroove 50 is circular or annular, and the cavity 54 is circular orannular, forming a concentric circle with the separation groove 50. Thisreduces electrostatic capacitance generated between the throughelectrode 34 and the semiconductor substrate 30, thus making it possibleto improve the conversion efficiency and suppress a delay (residualimage).

In addition, it is preferable that an impurity region (indicated by p+inFIG. 2) of a same conductivity type (n-type or p-type) as the throughelectrode 34 be provided in the semiconductor substrate 30 on the outersurface 51 of the separation groove 50. Furthermore, it is preferablethat the fixed charge layer 26 be provided on the outer surface 51, theinner surface 52, and the bottom surface 53 of the separation groove 50,and on the first surface 30A of the semiconductor substrate 30.Specifically, it is preferable to provide a p-type impurity region(indicated by p+in FIG. 2) in the semiconductor substrate 30 on theouter surface 51 of the separation groove 50, and to provide a filmhaving negative fixed charges as the fixed charge layer 26. This allowsfor reduction in a dark current.

In the solid-state imaging element 10 of the present embodiment, lightentering the organic photoelectric converter 20A from a side on whichthe top-electrode 25 is located is absorbed by a dye material includedin the photoelectric conversion layer 23A. In addition, thephotoelectric conversion layer 23A includes either a material serving asan electron donor or a material serving as an electron acceptor for thedye material. Excitons generated by light absorption of the dye materialare thereby disassociated to generate charges at an interface betweenthe dye material and the electron donor or at an interface between thedye material and the electron acceptor. The charges (electrons andholes) generated at the interface are each carried to a correspondingelectrode by diffusion resulting from a difference in concentration ofthe electrons, an internal electric field resulting from a difference inwork function between the bottom-electrode 21 and the top-electrode 25,or application of a voltage between the bottom-electrode 21 and thetop-electrode 25, and are detected as a photocurrent. It is alsopossible to control transport directions of the electrons and the holesby control of an internal electric field generated between thebottom-electrode 21 and the top-electrode 25.

In the following, description is given of the configurations, materials,etc. of respective components.

The organic photoelectric converter 20A is a photoelectric conversionelement that absorbs green light corresponding to a portion or theentirety of a selective wavelength range (for example, 495 nm to 570 nm)to generate the electron-hole pairs.

The bottom-electrode 21 is directly opposed to light receiving surfacesof the inorganic photoelectric converters 32B and 32R formed in thesemiconductor substrate 30, and is provided in regions covering thelight receiving surfaces. The bottom-electrode 21 is formed with use ofa conductive material having optical transparency (a transparentconductive material), and includes ITO (indium tin oxide), for example.However, in addition to ITO, a tin oxide (SnO₂)-based material to whicha dopant is added or a zinc oxide-based material prepared through addinga dopant to zinc oxide (ZnO) may be used as a constituent material ofthe bottom-electrode 21. Examples of the zinc oxide-based materialinclude aluminum zinc oxide (AZO) to which aluminum (Al) is added as adopant, gallium zinc oxide (GZO) to which gallium (Ga) is added, andindium zinc oxide (120) to which indium (In) is added. In addition tothese materials, indium-tungsten oxide (IWO), Cul, InSbO₄, ZnMgO,CuInO₂, MgIn₂O₄, CdO, ZnSnO₃, etc. may also be used. In the solid-stateimaging apparatus 1 that uses the solid-state imaging element 10 as onepixel, the bottom-electrode 21 may be separated for each pixel or may beformed as a common electrode for respective pixels.

The lower inter-layer 22 functions as a charge injection blocking layerthat suppresses injection of the charges from the bottom-electrode 21.For example, in a case where the bottom-electrode 21 is used as ananode, the lower inter-layer 22 functions as an electron injectionblocking layer that suppresses injection of electrons from thebottom-electrode 21. In this case, examples of a material that forms thelower inter-layer 22 include, a phenanthroline-based compound, analuminum quinoline-based compound, an oxadiazole-based compound, and asilole-based compound. It is preferable that a film thickness in astacking direction (hereinafter, simply referred to as a thickness) ofthe lower inter-layer 22 be, for example, in a range from 5 nm to 100 nmboth inclusive.

In a case where the bottom-electrode 21 is used as a cathode, the lowerinter-layer 22 functions as a hole injection blocking layer thatsuppresses injection of holes from the bottom-electrode 21. In thiscase, examples of the material included in the lower inter-layer 22include a naphthalene diimide-based material and a material includingpyridine, pyrimidine, or triazine, and more specific examples thereofinclude B3PyMPM (bis-4,6-(3,5-di-3-pyridylphenyl)-2-methylpyrimi-dine),etc. In addition, the material of the lower inter-layer 22 is notlimited to an organic semiconductor, and the lower inter-layer 22 may beformed with use of an oxide semiconductor such as ZnO, TiO₂, andInGaZnO. It is preferable that the lower inter-layer 22 have a thicknessin a range from 5 nm to 200 nm both inclusive, for example.

The photoelectric conversion layer 23A converts optical energy intoelectric energy. The photoelectric conversion layer 23 is formed withuse of the dye material absorbing light, and the electron acceptor orthe electron donor or both with respect to the dye material. Thephotoelectric conversion layer 23 is provided by mixing of the dyematerial and the electron acceptor, mixing of the dye material and theelectron donor, or mixing of the dye material, the electron acceptor,and the electron donor. The photoelectric conversion layer 23A has aso-called bulk hetero structure in a layer in which bonded surfaces ofthe dye material and the electron acceptor or bonded surfaces of the dyematerial and the electron donor, or both are formed. The photoelectricconversion layer 23A provides a field where excitons generated uponabsorption of light are dissociated into electrons and holes.Specifically, the excitons are dissociated into the electrons and theholes at the interface between the dye material and the electron donoror the interface between the dye material and the electron acceptor, orboth.

Examples of materials included in the photoelectronic conversion layer23A include quinacridone, boron subphthalocyanine chloride, boronatedboron subphthalocyanine pentacene, benzothieno-benzothiphene, fullerene,and derivatives thereof. The photoelectric conversion layer 23A includesa combination of two or more kinds of the foregoing organicsemiconductor materials. The foregoing organic semiconductor materialsfunction as a p-type semiconductor or an n-type semiconductor, dependingon the combination.

It is to be noted that the organic semiconductor material (a firstorganic semiconductor material) included in the photoelectric conversionlayer 23A is not limited, in particular. Besides the organicsemiconductor materials listed above, for example, any one kind ofnaphthalene, anthracene, phenantherene, tetracene, pyrene, perylene, andfluoranthene, and derivatives thereof is preferably used. Alternatively,a polymer such as phenylenevinylene, fluorene, carbazole, indole,pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene or aderivative thereof may be used. Additionally, it is possible topreferably use a metal complex dye, a cyanine-based dye, amerocyanine-based dye, a phenylxanthene-based dye, atriphenylmethane-based dye, a rhodacyanine-based dye, a xanthene-baseddye, a macrocyclic azaannulene-based dye, an azulene-based dye,naphthaquinone, an anthraquinone-based dye, a chain compound in which acondensed polycyclic aromatic group such as anthracene and pyrene and anaromatic ring or a heterocyclic compound are condensed, a cyanine-likedye bonded by two nitrogen-containing hetero rings such as quinoline,benzothiazole, and benzoxazole that have a squarylium group and croconicmethine group as a bonded chain, or by ae squarylium group or a croconicmethine group, etc. It is to be noted that the foregoing metal complexdye is preferably, but not limited to, a dithiol metal complex-baseddye, a metallophthalocyanine dye, a metalloporphyrine dye, or aruthenium complex dye. The photoelectric conversion layer 23A preferablyhas a thickness in a range from 50 nm to 500 nm both inclusive, forexample.

The upper inter-layer 24 functions as a charge injection blocking layerthat suppresses injection of charges from the top-electrode 25. As amaterial forming the upper inter-layer 24, an organic semiconductormaterial having no halogen atom in a molecule is preferably used.However, in a case where an organic semiconductor material (a secondorganic semiconductor material) having a halogen atom in a molecule isused, it is preferable that a concentration of the second organicsemiconductor material in the upper inter-layer 24 be less than 0.05volume %.

For example, the upper inter-layer 24 functions as a hole injectionblocking layer that suppresses injection of holes from the top-electrode25 in a case where the top-electrode 25 is used as a cathode electrode.In this case, examples of a material that forms the upper inter-layer 24include a naphthalene diimide-based material and a material includingpyridine, pyrimidine, or triazine, and more specific examples thereofinclude B3PyMPM (bis-4,6-(3,5-di-3-pyridylphenyl)-2-methylpyrimi-dine),etc. It is preferable that the upper inter-layer 24 have a thickness ina range from 5 nm to 100 nm both inclusive, for example.

In addition, the upper inter-layer 24 may be used for the purpose ofcontrolling an effective work function of the top-electrode, forexample. In this case, examples of a material that forms the upperinter-layer 24 include molybdenum oxide (MoO₂, MoP₃), tungsten oxide(WO₃), and HAT-CN (1,4,5,8,9,11-Hexaazatriphenylenehexacarbonitrile),etc. Formation of the upper inter-layer 24 using the foregoing materialmakes it possible to control a charge readout direction to cause thetop-electrode 25 to function as an anode.

It is to be noted that in a case where the top-electrode 25 is used asthe anode, an electron injection blocking layer may be provided betweenthe upper inter-layer 24 and the photoelectric conversion layer 23A.Examples of a material of the electron injection blocking layer includea phenanthroline-based compound, an aluminum quinoline-based compound,an oxadiazole-based compound, a silole-based compound, etc. It ispreferable that the electron injection blocking layer have a thicknessin a range from 5 nm to 100 nm both inclusive, for example.

Any layer other than the lower inter-layer 22, the photoelectricconversion layer 23A, and the upper inter-layer 24 may be provided inthe organic photoelectric converter 20A. As the other layers, to enhancecarrier injection blocking performance, for example, another carrierinjection blocking layer may be provided between the lower inter-layer22 and the photoelectric conversion layer 23A or between the upperinter-layer 24 and the photoelectric conversion layer 23A. The foregoingelectron injection blocking layer is a specific example of the carrierinjection blocking layer.

The top-electrode 25 is formed with use of a conductive material (atransparent conductive material) having optical transparency similar tothe bottom-electrode 21. Specific examples of the conductive materialincludes ITO (indium tin oxide), a tin oxide (SnO₂)-based material towhich a dopant is added or a zinc oxide-based material to which a dopantis added. Examples of the zinc oxide-based material include aluminumzinc oxide (AZO) to which aluminum (Al) is added as a dopant, galliumzinc oxide (GZO) to which gallium (Ga) is added, and indium zinc oxide(IZO) to which indium (In) is added. In addition to these materials,indium-tungsten oxide (IWO), CuI, InSbO₄, ZnMgO, CuInO₂, MgIn₂O₄, CdO,ZnSnO₃, etc. may also be used. It is preferable that the top-electrode25 have a thickness in a range from 10 nm to 200 nm both inclusive, forexample.

It is to be noted that although a plurality of materials are listed asthe materials of the respective layers that configure the organicphotoelectric converter 20A, it is preferable to select the materials ofthe respective layers to cause the organic photoelectric converter 20Aof the present embodiment to have an energy level as illustrated inFIGS. 3A and 3B, for example.

For example, in a case where the top-electrode 25 is used as thecathode, as illustrated in FIG. 3A, it is preferable that a workfunction (WF) of the top-electrode 25, electron affinity EA1 of theupper inter-layer 24, and electron affinity EA2 of an electron acceptormaterial included in the photoelectric conversion layer 23A have amagnitude relationship of EA2≤EA1≤WF. This makes it possible to satisfyboth enhancement of extraction efficiency (quantum efficiency) of signalcharges (herein, electrons) generated in the photoelectric conversionlayer 23A and reduction in a dark current. In addition, it is preferableto use a material in which an ionization potential (IP1) of the upperinter-layer 24 is larger than the work function (WF) of thetop-electrode 25 and an ionization potential (IP2) of an electron donormaterial included in the photoelectric conversion layer 23A. This makesit possible to efficiently suppress injection of the holes from thetop-electrode 25.

For example, in a case where the top-electrode 25 is used as the anode,as illustrated in (B) of FIG. 3, it is preferable to use a materialwhere the electron affinity EA1 of the upper inter-layer 24 is largerthan the work function (WF) of the top-electrode 25. This makes itpossible to satisfy both enhancement of extraction efficiency (quantumefficiency) of signal charges (herein, holes) generated in thephotoelectric conversion layer 23A and reduction in a dark current.

The fixed charge layer 26 may be a film having positive fixed charges ora film having negative fixed charges. Materials of the film having thenegative fixed charges include hafnium oxide, aluminum oxide, zirconiumoxide, tantalum oxide, titanium oxide, etc. In addition to the foregoingmaterials, lanthanum oxide, praseodymium oxide, cerium oxide, neodymiumoxide, promethium oxide, samarium oxide, europium oxide, gadoliniumoxide, terbium oxide, dysprosium oxide, holmium oxide, thulium oxide,ytterbium oxide, lutetium oxide, yttrium oxide, an aluminum nitridefilm, a hafnium oxynitride film, or an aluminum oxynitride film, etc.may also be used.

The fixed charge layer 26 may have a configuration in which two or morekinds of films are stacked. This makes it possible to further enhance afunction as a hole accumulation layer, for example, in the case of thefilm having the negative fixed charges.

Although materials of the dielectric layer 27 are not specificallylimited, the dielectric layer 27 is formed with use of, for example, asilicon oxide film, TEOS, a silicon nitride film, a silicon oxynitridefilm, etc.

The inter-layer insulating layer 28 includes, for example, asingle-layer film including one kind of silicon oxide, silicon nitride,silicon oxynitride (SiON) or the like, or a laminated film including twoor more kinds thereof.

The protective layer 29 includes a material having optical transparency,and includes, for example, a single-layer film including any of siliconoxide, silicon nitride, and silicon oxynitride (SiON), or a laminatedfilm including two or more kinds thereof. The protective layer 29 has athickness in a range from 100 nm to 30000 nm, for example.

The semiconductor substrate 30 includes a n-type silicon (Si) substrate,for example, and has a p-well 31 in a predetermined region. The verticaltype transistor Tr1, the transfer transistor Tr2, the amplifiertransistor AMP, and the reset transistor RST, etc., described above areprovided on the second surface 30B of the p-well 31. In addition,peripheral circuits (not illustrated) including a logic circuit, etc.,are provided in a periphery of the semiconductor substrate 30.

The inorganic photoelectric converters 32B and 32R each have a p/njunction in a predetermined region of the semiconductor substrate 30.The inorganic photoelectric converters 32B and 32R enable dispersion oflight in a longitudinal direction with use of a difference in wavelengthof absorbed light depending on a depth of light incidence in the siliconsubstrate. The inorganic photoelectric converter 32B selectively detectsblue light to accumulate signal charges corresponding to blue, and isdisposed at a depth that allows for efficient photoelectric conversionof blue light. The inorganic photoelectric converter 32R selectivelydetects red light to accumulate signal charge corresponding to red, andis disposed at a depth that allows for efficient photoelectricconversion of red light. It is to be noted that blue (B) and red (R) arecolors respectively corresponding to a wavelength range of 450 nm to 495nm, for example, and a wavelength range of 620 nm to 750 nm, forexample. It is only necessary to allow each of the inorganicphotoelectric converters 32B and 32R to detect light in a portion or theentirety of each of the wavelength ranges.

The inorganic photoelectric converter 32B includes a p+ region servingas a hole accumulation layer, and an n region serving as an electronaccumulation layer, for example. The inorganic photoelectric converter32R has a p+ region serving as a hole accumulation layer, and an nregion serving as an electron accumulation layer (has a stackingstructure of p-n-p), for example. The n region of the inorganicphotoelectric converter 32B is coupled to the vertical type transistorTr1. The p+ region of the inorganic photoelectric converter 32B bendsalong the vertical type transistor Tr1 and is connected to the p+ regionof the inorganic photoelectric converter 32R.

The vertical type transistor Tr1 is a transfer transistor thattransfers, to the floating diffusion FD1, signal charges (electrons inthe present embodiment) corresponding to blue generated and accumulatedin the inorganic photoelectric converter 32B. The inorganicphotoelectric converter 32B is formed at a position deep from the secondsurface 30B of the semiconductor substrate 30; therefore, the transfertransistor of the inorganic photoelectric converter 32B preferablyincludes the vertical type transistor Tr1.

The transfer transistor Tr2 transfers, to the floating diffusion FD2,signal charges (electrons in the present embodiment) corresponding tored generated and accumulated in the inorganic photoelectric converter32R, and includes a MOS transistor, for example.

The amplifier transistor AMP is a modulation element that modulates anamount of charges generated in the organic photoelectric converter 20Ainto voltage, and includes a MOS transistor, for example.

The reset transistor RST resets the charges transferred from the organicphotoelectric converter 20A to the floating diffusion FD3, and includesa MOS transistor, for example.

The first lower contact 35, the second lower contact 45, the third lowercontact 46, and the upper contact 36 each include, for example, a dopedsilicon material such as PDAS (Phosphorus Doped Amorphous Silicon) or ametal material such as aluminum (Al), tungsten (W), titanium (Ti),cobalt (Co), hafnium (Hf), and tantalum (Ta).

FIG. 4 is a plan view of a configuration example of the solid-stateimaging apparatus (the solid-state imaging apparatus 1, for example)having the unit pixel P in which a plurality of photoelectric converters(for example, the foregoing inorganic photoelectric converters 32B and32R and the foregoing organic photoelectric converter 20A) to which thetechnology according to the present disclosure may be applied arestacked. That is, FIG. 4 illustrates an example of a planarconfiguration of the unit pixel P that configures a pixel unit 1 aillustrated in FIG. 14, for example.

The unit pixel P includes a photoelectric conversion region 1100 where ared photoelectric converter (the inorganic photoelectric converter 32Rin FIG. 2), a blue photoelectric converter (the inorganic photoelectricconverter 32B in FIG. 2), and a green photoelectric converter (theorganic photoelectric converter 20A in FIG. 2) that photoelectricallyconvert light of respective wavelengths of R (Red), G (Green), and B(Blue) (any of which is not illustrated in FIG. 4) are stacked in threelayers in order of, for example, the green photoelectric converter, theblue photoelectric converter, and the red photoelectric converter from aside on which a light receiving surface (the light entering side S1 inFIG. 2). Furthermore, the unit pixel P includes a Tr group 1110, a Trgroup 1120, and a Tr group 1130 as charge readout units that read outcharges corresponding to the light of the respective wavelengths of RGBfrom the red photoelectric converter, the green photoelectric converter,and the blue photoelectric converter. In the solid-state imagingapparatus 1, in one unit pixel, dispersion in the longitudinaldirection, that is, dispersion of light of each of RGB in each of thelayers as the red photoelectric converter, the green photoelectricconverter, and the blue photoelectric converter, is performed.

The Tr group 1110, the Tr group 1120, and the Tr group 1130 are formedon the periphery of the photoelectric conversion region 1100. The Trgroup 1110 outputs, as a pixel signal, signal charges corresponding tolight of R generated and accumulated in the red photoelectric converter.The Tr group 1110 includes a transfer Tr (MOS FET) 1111, a reset Tr1112, an amplification Tr 1113, and a selection Tr 1114. The Tr group1120 outputs, as a pixel signal, signal charges corresponding to lightof B generated and accumulated in the blue photoelectric converter. TheTr group 1120 includes a transfer Tr 1121, a reset Tr 1122, anamplification Tr 1123, and a selection Tr 1124. The Tr group 1130outputs, as a pixel signal, signal charges corresponding to light of Ggenerated and accumulated in the green photoelectric converter. The Trgroup 1130 includes a transfer Tr 1131, a reset Tr 1132, anamplification Tr 1133, and a selection Tr 1134.

The transfer Tr 1111 includes a gate G, a source/drain region S/D, andan FD (floating diffusion) 1115(a source/drain region serving as a FD).The transfer Tr 1121 includes the gate G, the source/drain region S/Dand an FD 1125. The transfer Tr 1131 includes the gate G, the greenphotoelectric converter (that is, the source/drain region S/D coupled tothe green photoelectric converter) in the photoelectric conversionregion 1100, and an FD 1135. It is to be noted that the source/drainregion of the transfer Tr 1111 is coupled to the red photoelectricconverter in the photoelectric conversion region 1100, and thesource/drain region S/D of the transfer Tr 1121 is coupled to the bluephotoelectric converter in the photoelectric conversion region 1100.

Each of the reset Tr 1112, 1132, and 1122, the amplification Tr 1113,1133, and 1123, and the selection Tr 1114, 1134, and 1124 includes thegate G and a pair of source/drain regions S/D disposed to interpose thegate G therebetween.

The FD 1115, 1135, and 1125 are respectively coupled to the source/drainregions S/D serving as sources of the reset Tr 1112, 1132, and 1122, andare respectively coupled to the gates G of the amplification Tr 1113,1133, and 1123. A power source Vdd is coupled to each of thesource/drain region S/D common to the reset Tr 1112 and theamplification Tr 1113, the source/drain region S/D common to the resetTr 1132 and the amplification Tr 1133, and the source/drain region S/Dcommon to the reset Tr 1122 and the amplification Tr 1123. A VSL(vertical signal line) is coupled to each of the source/drain regionsS/D serving as sources of the selection Tr 1114, 1134, and 1124.

The technology according to the present disclosure is applicable to thesolid-state imaging apparatus as described above.

(1-2. Method of Manufacturing Solid-State Imaging Element)

It is possible to manufacture the solid-state imaging element 10 of thepresent embodiment in the following manner, for example.

FIG. 5 to FIG. 8 illustrate the method of manufacturing the slid-stateimaging element 10 in process order. First, as illustrated in FIG. 5,the p-well 31, for example, is formed as a well of a first conductivitytype in the semiconductor substrate 30, and the inorganic photoelectricconverters 32B and 32R of a second conductivity type (the n type, forexample) are formed in this p-well 31. The p+ region is formed in thevicinity of the first surface 30A of the semiconductor substrate 30.

In addition, also as illustrated in FIG. 5, an impurity region (ap+region) penetrating from the first surface 30A to the second surface30B of the semiconductor substrate 30 is formed in a region where thethrough electrode 34 and the separation groove 50 are to be formed.Furthermore, a high-concentration impurity region (a p++ region) isformed in a region where the upper end and the lower end of the throughelectrode 34 are to be formed.

As also illustrated in FIG. 5, on the second surface 30B of thesemiconductor substrate 30, n+ regions serving as the floatingdiffusions FD1 to FD3 are formed, and thereafter, a gate wiring layer 37including respective gates of a gate insulation layer 33, the verticaltype transistor Tr1, the transfer transistor Tr2, the amplifiertransistor AMP, and the reset transistor RST is formed. Thus, thevertical type transistor Tr1, the transfer transistor Tr2, the amplifiertransistor AMP, and the reset transistor RST are formed. Furthermore,the multilayer wiring 40 including the first lower contact 35, thesecond lower contact 45, the third lower contact 46, the wiring layers41 to 43 including the connection unit 41A, and the insulation layer 44is formed on the second surface 30B of the semiconductor substrate 30.

As a base substrate of the semiconductor substrate 30, an SOI (Siliconon Insulator) substrate in which the semiconductor substrate 30, anembedded oxide film (not illustrated), and a retaining substrate (notillustrated) are stacked is used. The embedded oxide film and theretaining substrate are not illustrated in FIG. 2, but are joined to thefirst surface 30A of the semiconductor substrate 30. Annealing treatmentis performed after ion implantation.

Next, a supporting substrate (not illustrated), another semiconductorbase substrate, or the like is joined to the side on which the secondsurface 30B is located of the semiconductor substrate 30 (a side onwhich the multilayer wiring 40 is located) and flipped from top tobottom. Subsequently, the semiconductor substrate 30 is separated fromthe embedded oxide film and the retaining substrate of the SOI substrateto cause the first surface 30A of the semiconductor substrate 30 to beexposed. It is possible to perform the above processes with technologiesused in a typical CMOS process such as ion implantation and CVD(Chemical Vapor Deposition).

Next, as illustrated in FIG. 6, the semiconductor substrate 30 isprocessed from the side on which the first surface 30A is located by dryetching, for example, to form the annular or circular separation groove50. The depth of the separation groove 50 preferably penetrates from thefirst surface 30A to the second surface 30B of the semiconductorsubstrate 30 to reach the gate insulation layer 33, as indicated by anarrow D50A of FIG. 6. Furthermore, to further enhance an insulatingeffect in the bottom surface 53 of the separation groove 50, theseparation groove 50 preferably penetrates through the semiconductorsubstrate 30 and the gate insulation layer 33 to reach the insulationlayer 44 of the multilayer wiring 40, as indicated by an arrow D50B ofFIG. 6. FIG. 6 illustrates a case where the separation groove 50penetrates through the semiconductor substrate 30 and the gateinsulation layer 33.

Subsequently, as illustrated in FIG. 7, for example, the negative fixedcharge layer 26 is formed on the outer surface 51, the inner surface 52,and the bottom surface 53 of the separation groove 50 and on the firstsurface 30A of the semiconductor substrate 30. Two or more kinds offilms may be stacked as the negative fixed charge layer 26. This makesit possible to further enhance a function as the hole accumulationlayer. After the negative fixed charge layer 26 is formed, thedielectric layer 27 having the outer dielectric layer 27A and the innerdielectric layer 27B is formed. At this time, the cavity 54 is formedbetween the outer dielectric layer 27A and the inner dielectric layer27B in the separation groove 50 through appropriately adjusting a filmthickness of the dielectric layer 27 and film-forming conditions.

Next, as illustrated in FIG. 8, the inter-layer insulating layer 28 isformed. Subsequently, the bottom-electrode 21, the lower inter-layer 22,the photoelectric conversion layer 23A, the upper inter-layer 24, thetop-electrode 25, and the protective layer 29 are formed on theinter-layer insulating layer 28. In addition, the upper contact 36 isformed and coupled to the upper end of the through electrode 34. Lastly,the optical member such as the planarization layer and the on-chip lens(not illustrated) are disposed. Thus, the solid-state imaging element 10illustrated in FIG. 2 is completed.

In the solid-state imaging element 10, in a case where light enters theorganic photoelectric converter 20A via the on-chip lens (notillustrated), the light passes through the organic photoelectricconverter 20A and the inorganic photoelectric converters 32B and 32R inorder, and each of green light, blue light, and red light isphotoelectrically converted in the course of passing. In the following,signal acquisition operations of the respective colors are described.

(Acquisition of Green Signal by Organic Photoelectric Converter 20)

Of the light entering the solid-state imaging element 10, first, greenlight is selectively detected (absorbed) and photoelectrically convertedin the organic photoelectric converter 20A.

The organic photoelectric converter 20A is coupled to the gate Gamp ofthe amplifier transistor AMP and the floating diffusion FD3 via thethrough electrode 34. Thus, herein, electrons of the electron-hole pairsgenerated in the organic photoelectric converter 20A is retrieved fromthe side on which the top-electrode 25 is located, transferred to theside on which the second surface 30B is located of the semiconductorsubstrate 30 via the through electrode 34, and accumulated in thefloating diffusion FD3. Simultaneously with this, the amount of chargesgenerated in the organic photoelectric converter 20A is modulated intovoltage by the amplifier transistor AMP.

In addition, the reset gate Grst of the reset transistor RST is disposedadjacent to the floating diffusion FD3. Accordingly, the chargesaccumulated in the floating diffusion FD3 are reset by the resettransistor RST.

Herein, the organic photoelectric converter 20A is coupled not only tothe amplifier transistor AMP but also to the floating diffusion FD3 viathe through electrode 34, thus making it possible for the resettransistor RST to easily reset the charges accumulated in the floatingdiffusion FD3.

In contrast, in a case where the through electrode 34 is not coupled tothe floating diffusion FD3, it is difficult to reset the chargesaccumulated in the floating diffusion FD3, causing the charges to bedrawn to a side on which the top-electrode 25 is located by applicationof a large voltage. This may damage the photoelectric conversion layer23A. In addition, a configuration that enables resetting in a shortperiod of time causes an increase dark time noise, thereby resulting ina trade-off; therefore, this configuration is difficult.

(Acquisition of Blue Signal and Red Signal by Inorganic PhotoelectricConverters 32B and 32R)

Subsequently, blue light and red light of the light having passedthrough the organic photoelectric converter 20A are absorbed andphotoelectrically converted in order respectively in the inorganicphotoelectric converter 32B and the inorganic photoelectric converter32R. In the inorganic photoelectric converter 32B, electronscorresponding to the incident blue light are accumulated in the n regionof the inorganic photoelectric converter 32B, and the accumulatedelectrons are transferred to the floating diffusion FD1 by the verticaltype transistor Tr 1. Similarly, in the inorganic photoelectricconverter 32R, electrons corresponding to the incident red light areaccumulated in the n region of the inorganic photoelectric converter32R, and the accumulated electrons are transferred to the floatingdiffusion FD2 by the transfer transistor Tr2.

(1-3. Workings and Effects)

In the solid-state imaging element using the organic semiconductormaterials, as described above, the photoelectric conversion layerincluding the p-type and n-type organic semiconductor materials isformed to allow for efficient charge generation and charge transport.Whether a certain organic semiconductor material used for thephotoelectric conversion layer functions as the p-type semiconductor orthe n-type semiconductor is determined by a relative relationshipbetween an energy level of the organic semiconductor material and anenergy level of a material used together.

In the organic semiconductor, a level difference between HOMO and LUMOcorresponds to a bandgap (Eg), and an energy difference between the HOMOand a vacuum level is referred to as an ionization potential (I) and theenergy difference between the LUMO and the vacuum level is referred toas electron affinity (χ). For example, in a case where one organicsemiconductor material of two kinds of organic semiconductor materialsincluded in the photoelectric conversion layer has higher electronaffinity than the other organic semiconductor material, the one organicsemiconductor material has a higher electron-withdrawing property thanthe other organic semiconductor material. Therefore, the one organicsemiconductor material functions as the n-type semiconductor and theother organic semiconductor material functions as the p-typesemiconductor. Examples of a method of causing the organic semiconductormaterial to have an n-type property include a method of introducing,into a molecule structure, a halogen atom having largeelectronegativity. For example, the above-described boronsubphthalocyanine chloride used with quinacridone functions as then-type semiconductor.

In addition, as described above, an organic photoelectric conversionelement is reported in which an electron blocking layer and a holeblocking layer are each provided between the photoelectric conversionlayer and a pair of electrodes to further enhance electron extractionefficiency. In the organic photoelectric conversion element having sucha configuration, to make it easier to extract charges (electrons)generated in the photoelectric conversion layer, it is desirable to formthe hole blocking layer using a material having a deeper LUMO value(high electron affinity) than an organic semiconductor material thatfunctions as the n-type semiconductor in the photoelectric conversionlayer. Therefore, in general, an organic semiconductor material having ahalogen atom in a molecule is also used for the material of the holeblocking layer.

However, in a case where the material (the organic semiconductormaterial) having the halogen atom in the molecule is used as thematerial of the organic semiconductor layer provided between the pair ofelectrodes, the halogen atom included in the molecule of the organicsemiconductor material may be desorbed due to exposure of the organicsemiconductor layer to ultraviolet rays used during formation of thetop-electrode or formation of the protection film. The desorbed halogenatom diffuses to the side on which the top-electrode is located. At thistime, in a case where the electrode material of the top-electrodeincludes a metal oxide including indium, such as ITO, the desorbedhalogen atom and the metal oxide react, causing a metal element to beeluted. The eluted metal element thermally diffuses into thephotoelectric conversion layer during manufacturing of the solid-stateimaging element. The metal element diffused into the photoelectricconversion layer causes deterioration in dark current characteristics.

It is conceivable that desorption of the halogen atom as described aboveoccurs most easily in a layer directly under the top-electrode (incontact with the top-electrode).

In contrast, in the present embodiment, the upper inter-layer 24 inwhich a concentration of the organic semiconductor material having thehalogen atom in the molecule is in a range from 0 volume % to less than0.05 volume % is provided between the photoelectric conversion layer 23Aand the top-electrode 25. This makes it possible to suppressmodification of metal oxide included in the top-electrode 25 and theorganic material included in the organic photoelectric converter 20A(for example, the organic semiconductor material included in the upperinter-layer 24) during formation of the top-electrode 25.

In the present embodiment, the upper inter-layer 24 in which theconcentration of the organic semiconductor material having the halogenatom in the molecule is in a range from 0 volume % to less than 0.05volume % is provided between the photoelectric conversion layer 23A andthe top-electrode 25, which thus suppresses the modification of themetal oxide included in the top-electrode 25 and the organicsemiconductor material included in the upper inter-layer 24 duringformation of the top-electrode 25. Therefore, the dark currentcharacteristics are improved, thereby making it possible to provide thesolid-state imaging element 10 having excellent electriccharacteristics.

Next, description is given of second to sixth embodiments. In thefollowing, same components as those in the foregoing first embodimentare denoted by same reference numerals, and description thereof isomitted where appropriate.

2. SECOND EMBODIMENT

FIG. 9 schematically illustrates a cross-sectional configuration of aphotoelectric converter 20B that configures a solid-state imagingelement according to the second embodiment of the present disclosure.Similarly to the foregoing first embodiment, the organic photoelectricconverter 20B of the present embodiment is of the so-called longitudinaldirection spectral type in which, for example, one organic photoelectricconverter 20B and two inorganic photoelectric converters 32B and 32R(see FIG. 2) are stacked in the longitudinal direction. In the presentembodiment, the photoelectric conversion layer 23B is configured withuse of an organic semiconductor material that has one or two or morehalogen atoms in a molecule.

Desorption of the halogen atom, as described in the foregoing firstembodiment, from the organic semiconductor layer that is providedbetween the pair of electrodes and configured with use of the materialhaving the halogen atom in the molecule also occurs in a case where thephotoelectric conversion layer 23B is formed with use of the organicsemiconductor material having the halogen atom in the molecule. In thiscase, using, as the material included in the photoelectric conversionlayer 23B, an organic semiconductor material in which binding energy ofthe halogen atom having the smallest binding energy of one or two ormore halogen atoms included in the molecule is 5.4 eV or higher makes itpossible to suppress modification of the metal oxide included in thetop-electrode 25 and the organic semiconductor material included in thephotoelectric conversion layer 23B during formation of the top-electrode25.

It is to be noted that similarly to the material of the photoelectricconversion layer 23A in the foregoing first embodiment, examples of thematerial of the photoelectric conversion layer 23B in the presentembodiment include quinacridone, boron subphthalocyanine chloride,pentacene, benzothieno-benzothiphene, fullerene, and derivativesthereof, except that the photoelectric conversion layer 23B has one ormore halogen atoms in the molecule.

As described above, in the present embodiment, the photoelectricconversion layer 23B is formed with sue of the organic semiconductormaterial having one or two or more halogen atoms in the molecule inwhich binding energy of the halogen atom having the smallest bindingenergy in the molecule is 5.4 eV or higher. Accordingly, the organicphotoelectric converter 20B has effects similar to those of theforegoing first embodiment.

3. THIRD EMBODIMENT

FIG. 10 schematically illustrates a cross-sectional configuration of aphotoelectric converter 20C that configures a solid-state imagingelement according to a third embodiment of the present disclosure.Similarly to the foregoing first embodiment, the organic photoelectricconverter 20C of the present embodiment is of the so-called longitudinaldirection spectral type in which, for example, one organic photoelectricconverter 20B and two inorganic photoelectric converters 32B and 32R(see FIG. 2) are stacked in the longitudinal direction. In the presentembodiment, a distance between the photoelectric conversion layer 23Band the top-electrode 25 is set to 5 nm or larger.

In a case where a material having a halogen atom in a molecule is usedas the material included in the photoelectric conversion layer 23, as inthe foregoing first embodiment, even if the concentration of the organicsemiconductor material having the halogen atom in the molecule in theupper inter-layer 24 is 0 volume %, desorption of the halogen atom inthe photoelectric conversion layer 23 may occur due to irradiation withultraviolet rays, etc. during formation of the top-electrode 25 or theprotective layer 29, thereby modifying the organic material included inthe top-electrode 25 or the solid-state imaging element 10.

In contrast, in the present embodiment, the upper inter-layer 24B thatis formed with use of a material having no halogen atom in a moleculeand has a thickness of 5 nm or larger is provided between thephotoelectric conversion layer 23 including the organic semiconductormaterial having the halogen atom in the molecule and the top-electrode25. Examples of the material included in the upper inter-layer 24include a material including a pyridine skeleton, a pyrimidine skeleton,or a triazine skeleton in a molecule. Specific examples thereof includeB3PyMPM (bis-4,6-(3,5-di-3-pyridylphenyl)-2-methylpyrimi-dine), B4P6mPM,etc.

As described above, in the present embodiment, the upper inter-layer 24Bhaving a thickness of 5 nm or larger is provided between thephotoelectric conversion layer 23 and the top-electrode 25, and as thematerial thereof, the organic semiconductor material having no halogenatom in the molecule is used. Accordingly, the organic photoelectricconverter 20C has effects similar to those in the foregoing firstembodiment.

It is to be noted that the present technology may have a configurationin which the first embodiment and the second embodiment are combined,the first embodiment and the third embodiment are combined, or the firstembodiment, the second embodiment, and the third embodiment arecombined.

4. FOURTH EMBODIMENT

FIG. 11 schematically illustrates a cross-sectional configuration of aphotoelectric converter 60 that configures a solid-state imaging elementaccording to a fourth embodiment of the present disclosure. Thesolid-state imaging element of the present embodiment configures onepixel (unit pixel P) in a solid-state imaging apparatus (the solid-stateimaging apparatus 1: see FIG. 16) such as a CMOS image sensor used in anelectronic apparatus such as a digital still camera and a video camera,for example.

(4-1. Configuration of Organic Photoelectric Converter)

Similarly to the foregoing first embodiment, the solid-state imagingelement of the present embodiment is of a so-called longitudinaldirection spectral type in which, for example, one organic photoelectricconverter 60 and two inorganic photoelectric converters 32B and 32R (seeFIG. 2) are stacked in the longitudinal direction. The organicphotoelectric converter 60 is provided on the side on which the firstsurface (the back side) 30A is located of the semiconductor substrate30. The inorganic photoelectric converters 32B and 32R are formed to beembedded in the semiconductor substrate 30, and are stacked in thethickness direction of the semiconductor substrate 30.

The organic photoelectric converter 60 of the present embodimentincludes a pair of electrodes (a bottom-electrode 61 and a top-electrode64), and an exciton blocking layer 62 and a photoelectric conversionlayer 63 provided between the pair of electrodes. In the presentembodiment, the photoelectric conversion layer 63 is configured by twolayers, i.e., an exciton generation layer 63A including a dye materialand a first semiconductor material and an exciton disassociation layer63B including a second semiconductor material.

In the solid-state imaging element of the present embodiment, lightentering the organic photoelectric converter 60 from a side on which thetop-electrode 64 is located is absorbed by the exciton generation layer63A of the photoelectric conversion layer 63. Excitons generated therebymove to the disassociation layer 63B, and are disassociated intoelectrons and holes. Charges (electrons and holes) generated here areeach carried to different electrodes by diffusion resulting from adifference in concentration of carriers or an internal electric fieldresulting from a difference in work function between a negativeelectrode (herein, the bottom-electrode 61) and a positive electrode(herein, the top-electrode 64), and are detected as a photocurrent. Inaddition, it is possible to control transport directions of theelectrons and the holes by application of a potential between thebottom-electrode 61 and the top-electrode 64.

In the following, description is given of the configurations, materials,etc, of respective components.

The organic photoelectric converter 60 is a photoelectric conversionelement that absorbs green light corresponding to a portion or theentirety of a selective wavelength range (for example, 495 nm to 570 nm)to generate the electron-hole pairs.

The bottom-electrode 61 is directly opposed to the light receivingsurfaces of the inorganic photoelectric converters 32B and 32R formed inthe semiconductor substrate 30, illustrated in FIG. 2, for example, andis provided in regions covering the light receiving surfaces. Thebottom-electrode 61 is configured with a conductive material havingoptical transparency (a transparent conductive material), and includesITO (indium tin oxide), for example. However, in addition to ITO, a tinoxide (SnO₂)-based material to which a dopant is added or a zincoxide-based material prepared through adding a dopant to aluminum zincoxide (ZnO) may be used as a constituent material of thebottom-electrode 61. Examples of the zinc oxide-based material includealuminum zinc oxide (AZO) to which aluminum (Al) is added as a dopant,gallium zinc oxide (GZO) to which gallium (Ga) is added, and indium zincoxide (IZO) to which indium (In) is added. In addition to thesematerials, aluminum (Al), Cul, InSbO₄, ZnMgO, CuInO₂, MgInO₂O₄, CdO,ZnSnO₃, etc. may also be used. In the solid-state imaging apparatus 1that uses the solid-state imaging element 10 as one pixel, thebottom-electrode 61 may be separated for each pixel or may be formed asa common electrode for respective pixels.

The exciton blocking layer 62 prevents the excitons generated in theexciton generation layer 63A, for example, from being deactivated by thebottom-electrode 61. In a case where a relation of energy levels of therespective layers that configure the organic photoelectric converter 60,for example, is established as illustrated in FIG. 12A and FIG. 12B tobe described later, an electron transport material is preferably used asa material that forms an exciton blocking layer 62A. Specific examplesof the electron transport material include Bathocuproine (BCP), 2,9-Bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthro line (NBphen),2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi),(8-Quinolinolato) lithium (Liq),2-(4-tert-Butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD),1,3-bis[5-(4-tert-butylphenyl)-2[1,3,4]oxadiazolyl] benzene (OXD-7),3-(Biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole(TAZ), 4,4′-Bis(4,6-diphenyl-1,3,5-triazin-2-yl) biphenyl (BTB),Bis-4,6-(3,5-di-4-pyridylphenyl)-2-methylpyrimidine (B4PyMPM), etc. Inaddition, for example, in a case where the relation of the energy levelsof the respective layers that configure the organic photoelectricconverter 60 is established as illustrated in FIG. 13A and FIG. 13B tobe described later, a hole transport material is preferably used.Specific examples of the hole transport material include triarylaminederivatives (such as TPD, NPB, and TAPC), carbazole derivatives (such asCBP and TCTA), and fluorene derivatives (such as BSBF). It is preferablethat the exciton blocking layer 62A have a thickness in a range from 1nm to 50 nm, for example.

The photoelectric conversion layer 63 converts optical energy intoelectric energy. As described above, the photoelectric conversion layer63 is configured by the two layers, i.e., the exciton generation layer63A and the exciton disassociation layer 63B. The exciton generationlayer 63A is a layer including the dye material and the firstsemiconductor material and has a bulk heterojunction interfaceconfigured by the dye material and the first semiconductor material.Light entering the organic photoelectric converter 60 is absorbed by thedye material at the bulk heterojunction interface, and transfer ofenergy to the first semiconductor material generates excitons on thefirst semiconductor material. The exciton disassociation layer 63Bincludes the second semiconductor material. In the excitondisassociation layer 63B, the excitons diffused from the excitongeneration layer 63A are disassociated into charges (electrons andholes). It is to be noted that as a positional relation of the excitongeneration layer 63A and the exciton disassociation layer 63B, theexciton disassociation layer 63B is preferably disposed on the lightentering side S1, for example. This is because density of the excitonsgenerated in the exciton generation layer 63A is high on a side on whichthe light entering surface is located, and a distance (diffusiondistance) at which the generated excitons move to the excitondisassociation layer 63B is preferably short in order to enhancephotoelectric conversion efficiency.

In the dye material and the first semiconductor material included in theexciton generation layer 63A, it is preferable that the firstsemiconductor material, for example, have a bandgap substantially equalto, or smaller than a bandgap of the dye material. This facilitatesenergy transfer from the dye material to the first semiconductormaterial. The first semiconductor material and the second semiconductormaterial are the p-type semiconductor or the n-type semiconductor, andare semiconductor materials that have polarities different from eachother. In addition, it is preferable that the first semiconductormaterial and the second semiconductor material have a difference inenergy level. This makes it possible to quickly transfer charges(electrons and holes) generated in the exciton disassociation layer 63Bto the bottom-electrode 61 and the top-electrode 64.

FIGS. 12A, 12B, 13A, and 13B each illustrate the exciton generationlayer 63A and the exciton disassociation layer 63B and a combination ofthe energy levels of the dye material, the first semiconductor material,and the second semiconductor material that are included therein. Forexample, in a case holes are used as charges, as illustrated in FIG.12A, it is preferable that the first semiconductor material included inthe exciton generation layer 63A have a deeper HOMO level and a deeperLUMO level than the second semiconductor material included in theexciton disassociation layer 63B. In a case of such a combination of theenergy levels, the first semiconductor material is the n-typesemiconductor and the second semiconductor material is the p-typesemiconductor. As for the energy level of the dye material, for example,the LUMO levels of the dye material and the first semiconductor materialmay be equal to each other, as illustrated in FIG. 12A, or the HOMOlevels of the dye material and the first semiconductor material may beequal to each other, as illustrated in FIG. 12B.

In a case where electrons are used as charges, as illustrated in FIG.13A, it is preferable that the first semiconductor material included inthe exciton generation layer 63A have a shallower HOMO level and ashallower LUMO level than the second semiconductor material included inthe exciton disassociation layer 63B. In a case of such a combination ofthe energy levels, the first semiconductor material is the p-typesemiconductor and the second semiconductor material is the n-typesemiconductor. As for the energy level of the dye material, for example,the LUMO levels of the dye material and the first semiconductor materialmay be equal to each other, as illustrated in FIG. 13A, or the HOMOlevels of the dye material and the first semiconductor material may beequal to each other, as illustrated in FIG. 13B.

The materials used as the first semiconductor material and the secondsemiconductor material are preferably organic materials, and include thefollowing materials in the case of the combination of the energy levelsillustrated in FIG. 12A. As the dye material, a material having a highlinear absorption coefficient of a maximal absorption wavelength in avisible light region is preferable. This makes it possible to increaseabsorption capacity of light in the visible light region in the organicphotoelectric converter 60 and have a sharp spectral shape. Examples ofsuch a material include subphthalocyanine or a derivative thereofexpressed by a general formula (1). Specific examples of the materialinclude F₆SubPcOC₆F₅. Examples of the first semiconductor material (then-type semiconductor) include fullerene or a derivative thereofexpressed by a general formula (2) or a general formula (3). Examples ofthe second semiconductor material (the p-type semiconductor) includethiophene or a derivative thereof expressed by a general formula (4). Itis to be noted that in the present disclosure, fullerene is treated asthe organic semiconductor material.

(R1 to R12 are each independently selected from a group configured of ahydrogen atom, a halogen atom, a straight-chain, branched, or cyclicalkyl group, a thioalkyl group, a thioaryl group, an aryl sulfonylgroup, an alkyl sulfonyl group, an amino group, an alkyl amino group, anaryl amino group, a hydroxy group, an alkoxy group, an acyl amino group,an acyloxy group, a phenyl group, a carboxy group, a carboxamide group,a carboalkoxy group, an acyl group, a sulfonyl group, a cyano group, anda nitro group, and any adjacent ones of R1 to R12 are optionally part ofa condensed aliphatic ring or a condensed aromatic ring. The condensedaliphatic ring or the condensed aromatic ring described above optionallyincludes one or more atoms other than carbon. M is boron or a divalentor trivalent metal. X is an anionic group.)

(R13 and R14 are each independently one of a hydrogen atom, a halogenatom, a straight-chain, branched, or cyclic alkyl group, a phenyl group,a group having a straight-chain or condensed ring aromatic compound, agroup having a halogen compound, a partial fluoroalkyl group, aperfluoroalkyl group, a silyl alkyl group, a silyl alkoxy group, an arylsilyl group, an aryl sulfanyl group, an alkyl sulfanyl group, an arylsulfonyl group, an alkyl sulfonyl group, an aryl sulfide group, an alkylsulfide group, an amino group, an alkyl amino group, an aryl aminogroup, a hydroxy group, an alkoxy group, an acyl amino group, an acyloxygroup, a carbonyl group, a carboxy group, a carboxamide group, acarboalkoxy group, an acyl group, a sulfonyl group, a cyano group, anitro group, a group having a chalcogen compound, a phosphine group, aphosphene group, and derivatives thereof. Each of n and m is an integerof 1 or larger.)

(R15 and R16 are each independently a hydrogen atom or a substituentgroup expressed by a formula (4′). R17 is an aromatic ring group or anaromatic ring group having a substituent group.)

It is to be noted that the material included in the photoelectricconversion layer 63 is not particularly limited. Besides the materialslisted above, examples of the material include naphthalene, anthracene,phenantherene, tetracene, pyrene, perylene, fluoranthene, andderivatives thereof. Alternatively, a polymer such as phenylenevinylene,fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene,acetylene, and diacetylene, or a derivative thereof may be used.Additionally, it is possible to preferably use a metal complex dye, acyanine-based dye, a merocyanine-based dye, a phenylxanthene-based dye,a triphenylmethane-based dye, a rhodacyanine-based dye, a xanthene-baseddye, a macrocyclic azaannulene-based dye, an azulene-based dye,naphthaquinone, an anthraquinone-based dye, a chain compound in which acondensed polycyclic aromatic group such as anthracene and pyrene and anaromatic ring or a heterocyclic compound are condensed, a cyanine-likedye bonded by two nitrogen-containing hetero rings such as quinoline,benzothiazole, and benzoxazole that have a squarylium group and croconicmethine group as a bonded chain, or by ae squarylium group or a croconicmethine group, etc. It is to be noted that the foregoing metal complexdye is preferably, but not limited to, a dithiol metal complex-baseddye, a metallophthalocyanine dye, a metalloporphyrine dye, or aruthenium complex dye.

It is preferable that the exciton generation layer 63A have thethickness in a range of 50 nm to 300 nm, for example. It is preferablethat the exciton disassociation layer 63B have a thickness in a rangefrom 5 nm to 100 nm, for example.

It is to be noted that any other layer, for example, a buffer film maybe provided between the photoelectric conversion layer 63 and thebottom-electrode 61 and between the photoelectric conversion layer 63and the top-electrode 64. In addition, for example, an undercoat layer,a hole transport layer, an electron blocking film, the photoelectricconversion layer 63, a hole blocking film, the buffer film, an electrontransport layer, a work coefficient adjustment film, etc. may also bestacked in order from side on which the bottom-electrode 61 is located.

The top-electrode 64 includes a conductive film having opticaltransparency similar to the bottom-electrode 61. In the solid-stateimaging apparatus 1 that uses the sold-state imaging element 10 as onepixel, the top-electrode 64 may be separated for each pixel, or may beformed as a common electrode for respective pixels. The top-electrode 64has a thickness in a range from 10 nm to 200 nm, for example.

(4-2. Workings and Effects)

In recent years, in the solid-state imaging apparatus such as a CCDimage sensor or a CMOS image sensor, high color reproducibility, a highframe rate, and high sensitivity have been in demand. To achieve them,an excellent spectral shape, high responsivity, and high externalquantum efficiency (EQE) are in demand.

For example, in an imaging element (a solid-state imaging element)having a stacking structure of an organic photoelectric conversion filmand an inorganic photoelectric converter that performs silicon bulkspectroscopy, the organic photoelectric conversion film in generalincludes two kinds of materials that function as the p-typesemiconductor or the n-type semiconductor. The organic photoelectricconversion film includes a bulk heterojunction interface (an P/Ninterface) formed, in a film, by the p-type semiconductor and the n-typesemiconductor. Excitons generated in the organic photoelectricconversion film by light absorption are disassociated (separated) intocarriers (electrons and holes) generated at the bulk heterojunctioninterface. Of the carriers generated at the bulk heterojunctioninterface, electrons are transported to one electrode by the n-typesemiconductor, and holes are transported to the other electrode by thep-type semiconductor.

To achieve high responsivity in the solid-state imaging element providedwith the organic photoelectric conversion film including the two kindsof materials (two elements), it is necessary for both the p-typesemiconductor and the n-type semiconductor to have high charge transportcharacteristics. Therefore, to achieve an excellent spectral shape, highresponsivity, and high external quantum efficiency, it is necessary foreither the p-type semiconductor or the n-type semiconductor to have bothsharp spectral characteristics and high charge mobility. However, ingeneral, a material having a sharp spectral shape in a solid film tendsnot to have high charge transport characteristics. Thus, it is extremelydifficult to achieve an excellent spectral shape, high responsivity, andhigh external quantum efficiency by the two kinds of materials.

Hence, a material having a sharp spectral shape (a dye material, forexample) is separately prepared, and a solid-state imaging elementprovided with an organic photoelectric conversion film including amixture of three kinds of materials (three elements), i.e., the dyematerial, and a p-type semiconductor and an n-type semiconductor thathave high charge transport characteristics is conceivable. For aphotoelectric conversion mechanism in the photoelectric conversion filmformed by mixing of the foregoing three kinds of materials, three paths(a path A, a path B, and a path C) are assumed. In the organicphotoelectric conversion film in which the three kinds of materials aremixed, first, the dye material absorbs light and enters an excitedstate. The dye material in the excited state may follow the three paths(the path A, the path B, and the path C) thereafter.

In the path A, energy is transferred from the dye material in theexcited state to the n-type semiconductor, and the n-type semiconductorenters the excited state. Thereafter, disassociation of excitons occursbetween the n-type semiconductor and the p-type semiconductor, and holesare generated on the p-type semiconductor and the electrons aregenerated on the n-type semiconductor. Each of the holes and theelectrons is transported to a corresponding electrode by an electricfield. It is to be noted that although a path where energy of the dyematerial is transferred to the p-type semiconductor is conceivable, ingeneral, the p-type semiconductor often has a wider bandgap than that ofthe dye material. Thus, energy transfer from the dye material to thep-type semiconductor is less likely to occur.

In the path B, disassociation of excitons occurs between the dyematerial and the p-type semiconductor, and electrons are generated onthe dye material and the holes are generated on the p-typesemiconductor. The electrons on the dye material move to the n-typesemiconductor for stabilization. Each of the holes on the p-typesemiconductor and the electrons having moved to the n-type semiconductoris transported to a corresponding electrode by an electric field,similarly to the path A.

In the path C, disassociation of excitons occurs between the dyematerial and the n-type semiconductor, and holes are generated on thedye material and electrons are generated on the n-type semiconductor.The holes on the dye material move to the p-type semiconductor forstabilization. Each of the electrons on the n-type semiconductor and theholes having moved to the p-type semiconductor is transported to acorresponding electrode by an electric field, similarly to the path A.

As described above, all reactions of the foregoing path A, the foregoingpath B, and the foregoing path C may occur in the organic photoelectricconversion film formed by mixing of the three kinds of materials.However, in general, carrier transport performance of the dye materialis low. Accordingly, in a case where the holes or the electrons aregenerated on the dye material as in the path B or the path C, expectedphotoelectric conversion efficiency or expected responsivity may not beachieved due to the low carrier transport performance.

1n contrast, in the present embodiment, the photoelectric conversionlayer 63 includes two layers, i.e., the exciton generation layer 63Aincluding the dye material and the p-type semiconductor or the n-typesemiconductor and the exciton disassociation layer 63B including then-type semiconductor or the p-type semiconductor. This achieves aconfiguration in which a light absorbing field (the exciton generationlayer 63A) and a charge generating field (the exciton disassociationlayer 63B) are separated, that is, a configuration in which the dyematerial is not in direct contact with a charge transport material (thesecond semiconductor material), thus causing the path A of the foregoingtwo paths to be selected.

As described above, in the present embodiment, the photoelectricconversion layer 63 including the exciton generation layer 63A and theexciton disassociation layer 63B is provided, thus reducing occurrenceof exciton disassociation on the dye material having low carriertransport performance. Therefore, disassociation of excitors easilyoccurs between the p-type semiconductor and the n-type semiconductorthat have high carrier transport performance, thus making it possible toenhance responsivity. In addition, it is also possible to enhancephotoelectric conversion efficiency.

In addition, in a case where a solid film in which a plurality ofmaterials are mixed is formed, a mixing state varies depending oncompatibility among the respective materials. In a case where the solidfilm including a plurality of materials is used as the photoelectricconversion layer, it is preferable that the solid film take a certainlevel of phase separation structure to cause a carrier transfer path(percolation) to function. In a case where the compatibility among therespective materials is high, however, the solid film is a layer inwhich the respective materials are uniformly mixed, and in a case wherethe compatibility among the respective materials is low, the solid filmis widely phase-separated. Both the cases are not desirable as thephotoelectric conversion layer. As described above, in a case where thephotoelectric conversion layer is formed with use of the mixture of thethree kinds of materials, it is difficult to control compatibility amongall the three kinds of materials to establish an ideal phase-separatingstructure.

In contrast, in the present embodiment, as described above, therespective layers (the exciton generation layer 63A and the excitondisassociation layer 63B) that configure the photoelectric conversionlayer 63 include not more than two kinds of materials, which thus makesit easy to establish a preferable phase-separating structure. Inaddition, flexibility in the combination of the materials is improved.

Furthermore, the photoelectric conversion layer 63 has a two-layerconfiguration (the exciton generation layer 63A and the excitondisassociation layer 63B) including not more than two kinds ofmaterials, which thus makes it possible to significantly simplify, forexample, a manufacturing apparatus, such as a vapor deposition source, apower source, and a control panel, prepared in a case where thephotoelectric conversion layer 63 is formed with use of a vapordeposition method, and a manufacturing method.

It is to be noted that the exciton generation layer 63A and the excitondissociation layer 63B may include materials other than theabove-described materials as far as the effects of the presentdisclosure are achievable.

5. FIFTH EMBODIMENT

FIG. 14 schematically illustrates a cross-sectional configuration of anorganic photoelectric converter 70 that configures a solid-state imagingelement according to a fifth embodiment of the present disclosure. Theorganic photoelectric converter 70 includes the pair of electrodes (thebottom-electrode 61 and the top-electrode 64) and a photoelectricconversion layer 73 provided between the pair of electrodes. In thepresent embodiment, the photoelectric conversion layer 73 differs fromthe foregoing fourth embodiment in that the photoelectric conversionlayer 73 includes an exciton generation layer 73A, an excitondisassociation layer 73B, and an inter-layer 73C (a first inter-layer)provided between the exciton generation layer 73A and the excitondisassociation layer 73B.

The inter-layer 73C prevents a dye material included in the excitongeneration layer 73A from being in contact with the second semiconductormaterial included in the exciton disassociation layer 7313. Theinter-layer 73C is configured with use of the first semiconductormaterial, for example. The inter-layer 73C has a thickness large enoughto prevent the dye material from being in contact with the secondsemiconductor material, and has a thickness in a range from 5 nm to 20nm, for example.

As described above, in general, the dye material has the low carriertransport performance. In contrast, in the present embodiment, asdescribed above, the inter-layer 73C including the first semiconductormaterial is provided between the exciton generation layer 73A and theexciton disassociation layer 73B. Preventing formation of an interfacebetween the dye material and the second semiconductor material in thismanner makes it possible to prevent disassociation of excitons on thedye material. Therefore, an effect of allowing for further enhancementof responsivity and photoelectric conversion efficiency is achieved, inaddition to the effects of the foregoing fourth embodiment.

6. SIXTH EMBODIMENT

FIG. 15 schematically illustrates a cross-sectional configuration of aphotoelectric converter 80 that configures a solid-state imaging elementaccording to a sixth embodiment of the present disclosure. Thephotoelectric converter 80 includes the pair of electrodes (thebottom-electrode 61 and the top-electrode 64) and a photoelectricconversion layer 83 provided between the pair of electrodes. The presentembodiment differs from the foregoing second and fifth embodiments inthat the photoelectric conversion layer 83 includes an excitongeneration layer 83A, an exciton disassociation layer 83B, and aninter-layer 83C, and that an inter-layer 83D (a second inter-layer) isfurther provided between the exciton disassociation layer 83B and theinter-layer 83C. It is to be noted that the inter-layer 83C has aconfiguration similar to that of the inter-layer 63C in the foregoingfifth embodiment.

The inter-layer 83D includes the first semiconductor material and thesecond semiconductor material. The inter-layer 83D has a bulkheterojunction interface configured by the first semiconductor materialand the second semiconductor material. The inter-layer 83D has athickness in a range from 5 nm to 50 nm, for example.

In the present embodiment, the inter-layer 83D including the firstsemiconductor and the second semiconductor is provided between theexciton disassociation layer 83B and the inter-layer 83C, thusincreasing an area of an interface where excitons are disassociated, andcharges are generated. This enhances separation speed from the excitonsto the charges, thus achieving an effect of allowing for furtherenhancement of responsivity, in addition to the effects of the foregoingfifth embodiment.

7. APPLICATION EXAMPLES Application Example 1

FIG. 16 illustrates an overall configuration of a solid-state imagingapparatus (the solid-state imaging apparatus 1) that uses, for each ofthe pixels, the solid-state imaging element (the solid-state imagingelement 10, for example) including the organic photoelectric converter20 (or the organic photoelectric converter 60, 70, or 80) described inthe foregoing first to sixth embodiments. The solid-state imagingapparatus 1 is a CMOS image sensor, and includes the pixel unit 1 a asan imaging region on the semiconductor substrate 30 and includes, in aperipheral region of the pixel unit 1 a, a peripheral circuit unit 130that includes, for example, a row scanner 131, a horizontal selector133, a column scanner 134, and a system controller 132.

The pixel unit 1 a has a plurality of unit pixels P (each correspondingto the solid-state imaging element 10) two-dimensionally arranged in amatrix, for example. The unit pixels P are wired with pixel drive linesLread (specifically, row selection lines and reset control lines) forrespective pixel rows and vertical signal lines Lsig for respectivepixel columns. The pixel drive lines Lread transmit drive signals forsignal reading from the pixels. The pixel drive lines each have one endcoupled to a corresponding one of output terminals, corresponding to therespective rows, of the row scanner 131.

The row scanner 131 includes a shift register, an address decoder, etc.and is a pixel driver, for example, that drives the respective pixels Pin the pixel unit 1 a on a row-by-row basis. A signal outputted fromeach of the pixels P of a pixel row selectively scanned by the rowscanner 131 is supplied to the horizontal selector 133 through each ofthe vertical signal lines Lsig. The horizontal selector 133 includes anamplifier, a horizontal selection switch, etc. provided for each of thevertical signal lines Lsig.

The column scanner 134 includes a shift register, an address decoder,etc., and drives horizontal selection switches of the horizontalselector 133 in sequence while scanning the horizontal selectionswitches. Such selective scanning by the column scanner 134 causes thesignals of the respective pixels transmitted through the respectivevertical signal lines Lsig to be outputted in sequence to a horizontalsignal line 135 and thereafter transmitted to outside of thesemiconductor substrate 30 through the horizontal signal line 135.

Circuit components including the row scanner 131, the horizontalselector 133, the column scanner 134, and the horizontal signal line 135may be formed directly on the semiconductor substrate 30 or disposed inan external control IC. Alternatively, the circuit components may beformed by any other substrate coupled by a cable, etc.

The system controller 132 receives a clock given from the outside of thesemiconductor substrate 30 or data etc. on instructions of operationmodes, and also outputs data such as internal information of thesolid-state imaging apparatus 1. The system controller 132 further has atiming generator that generates various timing signals, and performsdrive control of the peripheral circuits such as the row scanner 131,the horizontal selector 133, and the column scanner 134, on the basis ofthe various timing signals generated by the timing generator.

Application Example 2

The foregoing solid-state imaging apparatus 1 is applicable to variouskinds of electronic apparatuses having imaging functions. Examples ofthe electronic apparatuses include camera systems such as digital stillcameras and video cameras and mobile phones having the imagingfunctions. FIG. 17 illustrates, for purpose of an example, a schematicconfiguration of an electronic apparatus 2 (a camera). The electronicapparatus 2 is a video camera that enables shooting of a still image ora moving image, for example, and includes the solid-state imagingapparatus 1, an optical system (an optical lens) 310, a shutterapparatus 311, a driver 313 that drives the solid-state imagingapparatus 1 and the shutter apparatus 311, and a signal processor 312.

The optical system 310 guides image light (incident light) from anobject to the pixel unit 1 a of the solid-state imaging apparatus 1. Theoptical system 310 may include a plurality of optical lenses. Theshutter apparatus 311 controls a period in which the solid-state imagingapparatus 1 is irradiated with the light and a period in which the lightis blocked. The driver 313 controls a transfer operation of thesolid-state imaging apparatus 1 and a shutter operation of the shutterapparatus 311. The signal processor 312 performs various types of signalprocessing on signals outputted from the solid-state imaging apparatus1. An image signal Dout having been subjected to the signal processingis stored in a storage medium such as a memory or outputted to amonitor, etc.

Furthermore, the foregoing solid-state imaging element 10 including theorganic photoelectronic converter 20 (or the organic photoelectricconverter 60, 70, or 80) described in the foregoing first to sixthembodiments is applicable to the following electronic apparatuses (acapsule endoscope 10100, a mobile body of a vehicle, etc.).

Application Example 3 <Application Example to In-Vivo InformationAcquisition System>

FIG. 18 is a block diagram depicting an example of a schematicconfiguration of an in-vivo information acquisition system of a patientusing a capsule type endoscope, to which the technology according to anembodiment of the present disclosure (present technology) can beapplied.

The in-vivo information acquisition system 10001 includes a capsule typeendoscope 10100 and an external controlling apparatus 10200.

The capsule type endoscope 10100 is swallowed by a patient at the timeof inspection. The capsule type endoscope 10100 has an image pickupfunction and a wireless communication function and successively picks upan image of the inside of an organ such as the stomach or an intestine(hereinafter referred to as in-vivo image) at predetermined intervalswhile it moves inside of the organ by peristaltic motion for a period oftime until it is naturally discharged from the patient. Then, thecapsule type endoscope 10100 successively transmits information of thein-vivo image to the external controlling apparatus 10200 outside thebody by wireless transmission.

The external controlling apparatus 10200 integrally controls operationof the in-vivo information acquisition system 10001. Further, theexternal controlling apparatus 10200 receives information of an in-vivoimage transmitted thereto from the capsule type endoscope 10100 andgenerates image data for displaying the in-vivo image on a displayapparatus (not depicted) on the basis of the received information of thein-vivo image.

In the in-vivo information acquisition system 10001, an in-vivo imageimaged a state of the inside of the body of a patient can be acquired atany time in this manner for a period of time until the capsule typeendoscope 10100 is discharged after it is swallowed.

A configuration and functions of the capsule type endoscope 10100 andthe external controlling apparatus 10200 are described in more detailbelow.

The capsule type endoscope 10100 includes a housing 10101 of the capsuletype, in which a light source unit 10111, an image pickup unit 10112, animage processing unit 10113, a wireless communication unit 10114, apower feeding unit 10115, a power supply unit 10116 and a control unit10117 are accommodated.

The light source unit 10111 includes a light source such as, forexample, a light emitting diode (LED) and irradiates light on an imagepickup field-of-view of the image pickup unit 10112.

The image pickup unit 10112 includes an image pickup element and anoptical system including a plurality of lenses provided at a precedingstage to the image pickup element. Reflected light (hereinafter referredto as observation light) of light irradiated on a body tissue which isan observation target is condensed by the optical system and introducedinto the image pickup element. In the image pickup unit 10112, theincident observation light is photoelectrically converted by the imagepickup element, by which an image signal corresponding to theobservation light is generated. The image signal generated by the imagepickup unit 10112 is provided to the image processing unit 10113.

The image processing unit 10113 includes a processor such as a centralprocessing unit (CPU) or a graphics processing unit (GPU) and performsvarious signal processes for an image signal generated by the imagepickup unit 10112. The image processing unit 10113 provides the imagesignal for which the signal processes have been performed thereby as RAWdata to the wireless communication unit 10114.

The wireless communication unit 10114 performs a predetermined processsuch as a modulation process for the image signal for which the signalprocesses have been performed by the image processing unit 10113 andtransmits the resulting image signal to the external controllingapparatus 10200 through an antenna 10114A. Further, the wirelesscommunication unit 10114 receives a control signal relating to drivingcontrol of the capsule type endoscope 10100 from the externalcontrolling apparatus 10200 through the antenna 10114A. The wirelesscommunication unit 10114 provides the control signal received from theexternal controlling apparatus 10200 to the control unit 10117.

The power feeding unit 10115 includes an antenna coil for powerreception, a power regeneration circuit for regenerating electric powerfrom current generated in the antenna coil, a voltage booster circuitand so forth. The power feeding unit 10115 generates electric powerusing the principle of non-contact charging.

The power supply unit 10116 includes a secondary battery and storeselectric power generated by the power feeding unit 10115. In FIG. 18, inorder to avoid complicated illustration, an arrow mark indicative of asupply destination of electric power from the power supply unit 10116and so forth are omitted. However, electric power stored in the powersupply unit 10116 is supplied to and can be used to drive the lightsource unit 10111, the image pickup unit 10112, the image processingunit 10113, the wireless communication unit 10114 and the control unit10117.

The control unit 10117 includes a processor such as a CPU and suitablycontrols driving of the light source unit 10111, the image pickup unit10112, the image processing unit 10113, the wireless communication unit10114 and the power feeding unit 10115 in accordance with a controlsignal transmitted thereto from the external controlling apparatus10200.

The external controlling apparatus 10200 includes a processor such as aCPU or a GPU, a microcomputer, a control board or the like in which aprocessor and a storage element such as a memory are mixedlyincorporated. The external controlling apparatus 10200 transmits acontrol signal to the control unit 10117 of the capsule type endoscope10100 through an antenna 10200A to control operation of the capsule typeendoscope 10100. In the capsule type endoscope 10100, an irradiationcondition of light upon an observation target of the light source unit10111 can be changed, for example, in accordance with a control signalfrom the external controlling apparatus 10200. Further, an image pickupcondition (for example, a frame rate, an exposure value or the like ofthe image pickup unit 10112) can be changed in accordance with a controlsignal from the external controlling apparatus 10200. Further, thesubstance of processing by the image processing unit 10113 or acondition for transmitting an image signal from the wirelesscommunication unit 10114 (for example, a transmission interval, atransmission image number or the like) may be changed in accordance witha control signal from the external controlling apparatus 10200.

Further, the external controlling apparatus 10200 performs various imageprocesses for an image signal transmitted thereto from the capsule typeendoscope 10100 to generate image data for displaying a picked upin-vivo image on the display apparatus. As the image processes, varioussignal processes can be performed such as, for example, a developmentprocess (demosaic process), an image quality improving process(bandwidth enhancement process, a super-resolution process, a noisereduction (NR) process and/or image stabilization process) and/or anenlargement process (electronic zooming process). The externalcontrolling apparatus 10200 controls driving of the display apparatus tocause the display apparatus to display a picked up in-vivo image on thebasis of generated image data. Alternatively, the external controllingapparatus 10200 may also control a recording apparatus (not depicted) torecord generated image data or control a printing apparatus (notdepicted) to output generated image data by printing.

The description has been given above of one example of the in-vivoinformation acquisition system, to which the technology according to thepresent disclosure can be applied. The technology according to thepresent disclosure is applicable to, for example, the image pickup unit10112 of the configurations described above. This makes it possible toacquire a fine operative image having higher color reproducibility,thereby improving accuracy of an inspection.

Application Example 4 4. Application Example to Endoscopic SurgerySystem

The technology according to the present disclosure is applicable tovarious products. For example, the technology according to the presentdisclosure may be applied to an endoscopic surgery system.

FIG. 19 is a view depicting an example of a schematic configuration ofan endoscopic surgery system to which the technology according to anembodiment of the present disclosure (present technology) can beapplied.

In FIG. 19, a state is illustrated in which a surgeon (medical doctor)11131 is using an endoscopic surgery system 11000 to perform surgery fora patient 11132 on a patient bed 11133. As depicted, the endoscopicsurgery system 11000 includes an endoscope 11100, other surgical tools11110 such as a pneumoperitoneum tube 11111 and an energy treatment tool11112, a supporting arm apparatus 11120 which supports the endoscope11100 thereon, and a cart 11200 on which various apparatus forendoscopic surgery are mounted.

The endoscope 11100 includes a lens barrel 11101 having a region of apredetermined length from a distal end thereof to be inserted into abody lumen of the patient 11132, and a camera head 11102 connected to aproximal end of the lens barrel 11101. In the example depicted, theendoscope 11100 is depicted which includes as a hard mirror having thelens barrel 11101 of the hard type. However, the endoscope 11100 mayotherwise be included as a soft mirror having the lens barrel 11101 ofthe soft type.

The lens barrel 11101 has, at a distal end thereof, an opening in whichan objective lens is fitted. A light source apparatus 11203 is connectedto the endoscope 11100 such that light generated by the light sourceapparatus 11203 is introduced to a distal end of the lens barrel 11101by a light guide extending in the inside of the lens barrel 11101 and isirradiated toward an observation target in a body lumen of the patient11132 through the objective lens. It is to be noted that the endoscope11100 may be a direct view mirror or may be a perspective view mirror ora side view mirror.

An optical system and an image pickup element are provided in the insideof the camera head 11102 such that reflected light (observation light)from the observation target is condensed on the image pickup element bythe optical system. The observation light is photo-electricallyconverted by the image pickup element to generate an electric signalcorresponding to the observation light, namely, an image signalcorresponding to an observation image. The image signal is transmittedas RAW data to a CCU 11201.

The CCU 11201 includes a central processing unit (CPU), a graphicsprocessing unit (GPU) or the like and integrally controls operation ofthe endoscope 11100 and a display apparatus 11202. Further, the CCU11201 receives an image signal from the camera head 11102 and performs,for the image signal, various image processes for displaying an imagebased on the image signal such as, for example, a development process(demosaic process).

The display apparatus 11202 displays thereon an image based on an imagesignal, for which the image processes have been performed by the CCU11201, under the control of the CCU 11201.

The light source apparatus 11203 includes a light source such as, forexample, a light emitting diode (LED) and supplies irradiation lightupon imaging of a surgical region to the endoscope 11100.

An inputting apparatus 11204 is an input interface for the endoscopicsurgery system 11000. A user can perform inputting of various kinds ofinformation or instruction inputting to the endoscopic surgery system11000 through the inputting apparatus 11204. For example, the user wouldinput an instruction or a like to change an image pickup condition (typeof irradiation light, magnification, focal distance or the like) by theendoscope 11100.

A treatment tool controlling apparatus 11205 controls driving of theenergy treatment tool 11112 for cautery or incision of a tissue, sealingof a blood vessel or the like. A pneumoperitoneum apparatus 11206 feedsgas into a body lumen of the patient 11132 through the pneumoperitoneumtube 11111 to inflate the body lumen in order to secure the field ofview of the endoscope 11100 and secure the working space for thesurgeon. A recorder 11207 is an apparatus capable of recording variouskinds of information relating to surgery. A printer 11208 is anapparatus capable of printing various kinds of information relating tosurgery in various forms such as a text, an image or a graph.

It is to be noted that the light source apparatus 11203 which suppliesirradiation light when a surgical region is to be imaged to theendoscope 11100 may include a white light source which includes, forexample, an LED, a laser light source or a combination of them. Where awhite light source includes a combination of red, green, and blue (RGB)laser light sources, since the output intensity and the output timingcan be controlled with a high degree of accuracy for each color (eachwavelength), adjustment of the white balance of a picked up image can beperformed by the light source apparatus 11203. Further, in this case, iflaser beams from the respective RGB laser light sources are irradiatedtime-divisionally on an observation target and driving of the imagepickup elements of the camera head 11102 are controlled in synchronismwith the irradiation timings. Then images individually corresponding tothe R, G and B colors can be also picked up time-divisionally. Accordingto this method, a color image can be obtained even if color filters arenot provided for the image pickup element.

Further, the light source apparatus 11203 may be controlled such thatthe intensity of light to be outputted is changed for each predeterminedtime. By controlling driving of the image pickup element of the camerahead 11102 in synchronism with the timing of the change of the intensityof light to acquire images time-divisionally and synthesizing theimages, an image of a high dynamic range free from underexposed blockedup shadows and overexposed highlights can be created.

Further, the light source apparatus 11203 may be configured to supplylight of a predetermined wavelength band ready for special lightobservation. In special light observation, for example, by utilizing thewavelength experimental examplecy of absorption of light in a bodytissue to irradiate light of a narrow band in comparison withirradiation light upon ordinary observation (namely, white light),narrow band observation (narrow band imaging) of imaging a predeterminedtissue such as a blood vessel of a superficial portion of the mucousmembrane or the like in a high contrast is performed. Alternatively, inspecial light observation, fluorescent observation for obtaining animage from fluorescent light generated by irradiation of excitationlight may be performed. In fluorescent observation, it is possible toperform observation of fluorescent light from a body tissue byirradiating excitation light on the body tissue (autofluorescenceobservation) or to obtain a fluorescent light image by locally injectinga reagent such as indocyanine green (ICG) into a body tissue andirradiating excitation light corresponding to a fluorescent lightwavelength of the reagent upon the body tissue.

The light source apparatus 11203 can be configured to supply suchnarrow-band light and/or excitation light suitable for special lightobservation as described above.

FIG. 20 is a block diagram depicting an example of a functionalconfiguration of the camera head 11102 and the CCU 11201 depicted inFIG. 19.

The camera head 11102 includes a lens unit 11401, an image pickup unit11402, a driving unit 11403, a communication unit 11404 and a camerahead controlling unit 11405. The CCU 11201 includes a communication unit11411, an image processing unit 11412 and a control unit 11413. Thecamera head 11102 and the CCU 11201 are connected for communication toeach other by a transmission cable 11400.

The lens unit 11401 is an optical system, provided at a connectinglocation to the lens barrel 11101. Observation light taken in from adistal end of the lens barrel 11101 is guided to the camera head 11102and introduced into the lens unit 11401. The lens unit 11401 includes acombination of a plurality of lenses including a zoom lens and afocusing lens.

The number of image pickup elements which is included by the imagepickup unit 11402 may be one (single-plate type) or a plural number(multi-plate type). Where the image pickup unit 11402 is configured asthat of the multi-plate type, for example, image signals correspondingto respective R, G and B are generated by the image pickup elements, andthe image signals may be synthesized to obtain a color image. The imagepickup unit 11402 may also be configured so as to have a pair of imagepickup elements for acquiring respective image signals for the right eyeand the left eye ready for three dimensional (3D) display. If 3D displayis performed, then the depth of a living body tissue in a surgicalregion can be comprehended more accurately by the surgeon 11131. It isto be noted that, where the image pickup unit 11402 is configured asthat of stereoscopic type, a plurality of systems of lens units 11401are provided corresponding to the individual image pickup elements.

Further, the image pickup unit 11402 may not necessarily be provided onthe camera head 11102. For example, the image pickup unit 11402 may beprovided immediately behind the objective lens in the inside of the lensbarrel 11101.

The driving unit 11403 includes an actuator and moves the zoom lens andthe focusing lens of the lens unit 11401 by a predetermined distancealong an optical axis under the control of the camera head controllingunit 11405. Consequently, the magnification and the focal point of apicked up image by the image pickup unit 11402 can be adjusted suitably.

The communication unit 11404 includes a communication apparatus fortransmitting and receiving various kinds of information to and from theCCU 11201. The communication unit 11404 transmits an image signalacquired from the image pickup unit 11402 as RAW data to the CCU 11201through the transmission cable 11400.

In addition, the communication unit 11404 receives a control signal forcontrolling driving of the camera head 11102 from the CCU 11201 andsupplies the control signal to the camera head controlling unit 11405.The control signal includes information relating to image pickupconditions such as, for example, information that a frame rate of apicked up image is designated, information that an exposure value uponimage picking up is designated and/or information that a magnificationand a focal point of a picked up image are designated.

It is to be noted that the image pickup conditions such as the framerate, exposure value, magnification or focal point may be designated bythe user or may be set automatically by the control unit 11413 of theCCU 11201 on the basis of an acquired image signal. In the latter case,an auto exposure (AE) function, an auto focus (AF) function and an autowhite balance (AWB) function are incorporated in the endoscope 11100.

The camera head controlling unit 11405 controls driving of the camerahead 11102 on the basis of a control signal from the CCU 11201 receivedthrough the communication unit 11404.

The communication unit 11411 includes a communication apparatus fortransmitting and receiving various kinds of information to and from thecamera head 11102. The communication unit 11411 receives an image signaltransmitted thereto from the camera head 11102 through the transmissioncable 11400.

Further, the communication unit 11411 transmits a control signal forcontrolling driving of the camera head 11102 to the camera head 11102.The image signal and the control signal can be transmiued by electricalcommunication, optical communication or the like.

The image processing unit 11412 performs various image processes for animage signal in the form of RAW data transmitted thereto from the camerahead 11102.

The control unit 11413 performs various kinds of control relating toimage picking up of a surgical region or the like by the endoscope 11100and display of a picked up image obtained by image picking up of thesurgical region or the like. For example, the control unit 11413 createsa control signal for controlling driving of the camera head 11102.

Further, the control unit 11413 controls, on the basis of an imagesignal for which image processes have been performed by the imageprocessing unit 11412, the display apparatus 11202 to display a pickedup image in which the surgical region or the like is imaged. Thereupon,the control unit 11413 may recognize various objects in the picked upimage using various image recognition technologies. For example, thecontrol unit 11413 can recognize a surgical tool such as forceps, aparticular living body region, bleeding, mist when the energy treatmenttool 11112 is used and so forth by detecting the shape, color and soforth of edges of objects included in a picked up image. The controlunit 11413 may cause, when it controls the display apparatus 11202 todisplay a picked up image, various kinds of surgery supportinginformation to be displayed in an overlapping manner with an image ofthe surgical region using a result of the recognition. Where surgerysupporting information is displayed in an overlapping manner andpresented to the surgeon 11131, the burden on the surgeon 11131 can bereduced and the surgeon 11131 can proceed with the surgery withcertainty.

The transmission cable 11400 which connects the camera head 11102 andthe CCU 11201 to each other is an electric signal cable ready forcommunication of an electric signal, an optical fiber ready for opticalcommunication or a composite cable ready for both of electrical andoptical communications.

Here, while, in the example depicted, communication is performed bywired communication using the transmission cable 11400, thecommunication between the camera head 11102 and the CCU 11201 may beperformed by wireless communication.

In the foregoing, the description has been given of one example of theendoscopic surgery system to which the technology according to thepresent disclosure can be applied. The technology according to thepresent disclosure may be applied to the image pickup unit 11402 amongthe components of the configuration described above. Applying thetechnology according to the present disclosure to the image pickup unit11402 makes it possible to obtain a clearer image of the surgicalregion. Hence, it is possible for the surgeon to confirm the surgicalregion with certainty.

Note that the description has been given above of the endoscopic surgerysystem as one example. The technology according to the presentdisclosure may be applied to any medical system besides the endoscopicsurgery system, such as a micrographic surgery system.

Application Example 5 <Application Example to Mobile Body>

The technology (present technology) according to the present disclosureis applicable to various products. For example, the technology accordingto the present disclosure may be achieved in the form of an apparatus tobe mounted to a mobile body of any kind such as an automobile, anelectric vehicle, a hybrid electric vehicle, a motorcycle, bicycle, apersonal mobility, an airplane, an unmanned aerial vehicle, a vessel,and a robot.

FIG. 21 is a block diagram depicting an example of schematicconfiguration of a vehicle control system as an example of a mobile bodycontrol system to which the technology according to an embodiment of thepresent disclosure can be applied.

The vehicle control system 12000 includes a plurality of electroniccontrol units connected to each other via a communication network 12001.In the example depicted in FIG. 21, the vehicle control system 12000includes a driving system control unit 12010, a body system control unit12020, an outside-vehicle information detecting unit 12030, anin-vehicle information detecting unit 12040, and an integrated controlunit 12050. In addition, a microcomputer 12051, a sound/image outputsection 12052, and a vehicle-mounted network interface (1/F) 12053 areillustrated as a functional configuration of the integrated control unit12050.

The driving system control unit 12010 controls the operation of devicesrelated to the driving system of the vehicle in accordance with variouskinds of programs. For example, the driving system control unit 12010functions as a control device for a driving force generating device forgenerating the driving force of the vehicle, such as an internalcombustion engine, a driving motor, or the like, a driving forcetransmitting mechanism for transmitting the driving force to wheels, asteering mechanism for adjusting the steering angle of the vehicle, abraking device for generating the braking force of the vehicle, and thelike.

The body system control unit 12020 controls the operation of variouskinds of devices provided to a vehicle body in accordance with variouskinds of programs. For example, the body system control unit 12020functions as a control device for a keyless entry system, a smart keysystem, a power window device, or various kinds of lamps such as aheadlamp, a backup lamp, a brake lamp, a turn signal, a fog lamp, or thelike. In this case, radio waves transmitted from a mobile device as analternative to a key or signals of various kinds of switches can beinput to the body system control unit 12020. The body system controlunit 12020 receives these input radio waves or signals, and controls adoor lock device, the power window device, the lamps, or the like of thevehicle.

The outside-vehicle information detecting unit 12030 detects informationabout the outside of the vehicle including the vehicle control system12000. For example, the outside-vehicle information detecting unit 12030is connected with an imaging section 12031. The outside-vehicleinformation detecting unit 12030 makes the imaging section 12031 imagean image of the outside of the vehicle, and receives the imaged image.On the basis of the received image, the outside-vehicle informationdetecting unit 12030 may perform processing of detecting an object suchas a human, a vehicle, an obstacle, a sign, a character on a roadsurface, or the like, or processing of detecting a distance thereto.

The imaging section 12031 is an optical sensor that receives light, andwhich outputs an electric signal corresponding to a received lightamount of the light. The imaging section 12031 can output the electricsignal as an image, or can output the electric signal as informationabout a measured distance. In addition, the light received by theimaging section 12031 may be visible light, or may be invisible lightsuch as infrared rays or the like.

The in-vehicle information detecting unit 12040 detects informationabout the inside of the vehicle. The in-vehicle information detectingunit 12040 is, for example, connected with a driver state detectingsection 12041 that detects the state of a driver. The driver statedetecting section 12041, for example, includes a camera that images thedriver. On the basis of detection information input from the driverstate detecting section 12041, the in-vehicle information detecting unit12040 may calculate a degree of fatigue of the driver or a degree ofconcentration of the driver, or may determine whether the driver isdozing.

The microcomputer 12051 can calculate a control target value for thedriving force generating device, the steering mechanism, or the brakingdevice on the basis of the information about the inside or outside ofthe vehicle which information is obtained by the outside-vehicleinformation detecting unit 12030 or the in-vehicle information detectingunit 12040, and output a control command to the driving system controlunit 12010. For example, the microcomputer 12051 can perform cooperativecontrol intended to implement functions of an advanced driver assistancesystem (ADAS) which functions include collision avoidance or shockmitigation for the vehicle, following driving based on a followingdistance, vehicle speed maintaining driving, a warning of collision ofthe vehicle, a warning of deviation of the vehicle from a lane, or thelike.

In addition, the microcomputer 12051 can perform cooperative controlintended for automatic driving, which makes the vehicle to travelautonomously without depending on the operation of the driver, or thelike, by controlling the driving force generating device, the steeringmechanism, the braking device, or the like on the basis of theinformation about the outside or inside of the vehicle which informationis obtained by the outside-vehicle information detecting unit 12030 orthe in-vehicle information detecting unit 12040.

In addition, the microcomputer 12051 can output a control command to thebody system control unit 12020 on the basis of the information about theoutside of the vehicle which information is obtained by theoutside-vehicle information detecting unit 12030. For example, themicrocomputer 12051 can perform cooperative control intended to preventa glare by controlling the headlamp so as to change from a high beam toa low beam, for example, in accordance with the position of a precedingvehicle or an oncoming vehicle detected by the outside-vehicleinformation detecting unit 12030.

The sound/image output section 12052 transmits an output signal of atleast one of a sound and an image to an output device capable ofvisually or auditorily notifying information to an occupant of thevehicle or the outside of the vehicle. In the example of FIG. 21, anaudio speaker 12061, a display section 12062, and an instrument panel12063 are illustrated as the output device. The display section 12062may, for example, include at least one of an on-board display and ahead-up display.

FIG. 22 is a diagram depicting an example of the installation positionof the imaging section 12031.

In FIG. 22, the imaging section 12031 includes imaging sections 12101,12102, 12103, 12104, and 12105.

The imaging sections 12101, 12102, 12103, 12104, and 12105 are, forexample, disposed at positions on a front nose, sideview mirrors, a rearbumper, and a back door of the vehicle 12100 as well as a position on anupper portion of a windshield within the interior of the vehicle. Theimaging section 12101 provided to the front nose and the imaging section12105 provided to the upper portion of the windshield within theinterior of the vehicle obtain mainly an image of the front of thevehicle 12100. The imaging sections 12102 and 12103 provided to thesideview mirrors obtain mainly an image of the sides of the vehicle12100. The imaging section 12104 provided to the rear bumper or the backdoor obtains mainly an image of the rear of the vehicle 12100. Theimaging section 12105 provided to the upper portion of the windshieldwithin the interior of the vehicle is used mainly to detect a precedingvehicle, a pedestrian, an obstacle, a signal, a traffic sign, a lane, orthe like.

Incidentally, FIG. 22 depicts an example of photographing ranges of theimaging sections 12101 to 12104. An imaging range 12111 represents theimaging range of the imaging section 12101 provided to the front nose.Imaging ranges 12112 and 12113 respectively represent the imaging rangesof the imaging sections 12102 and 12103 provided to the sideviewmirrors. An imaging range 12114 represents the imaging range of theimaging section 12104 provided to the rear bumper or the back door. Abird's-eye image of the vehicle 12100 as viewed from above is obtainedby superimposing image data imaged by the imaging sections 12101 to12104, for example.

At least one of the imaging sections 12101 to 12104 may have a functionof obtaining distance information. For example, at least one of theimaging sections 12101 to 12104 may be a stereo camera constituted of aplurality of imaging elements, or may be an imaging element havingpixels for phase difference detection.

For example, the microcomputer 12051 can determine a distance to eachthree-dimensional object within the imaging ranges 12111 to 12114 and atemporal change in the distance (relative speed with respect to thevehicle 12100) on the basis of the distance information obtained fromthe imaging sections 12101 to 12104, and thereby extract, as a precedingvehicle, a nearest three-dimensional object in particular that ispresent on a traveling path of the vehicle 12100 and which travels insubstantially the same direction as the vehicle 12100 at a predeterminedspeed (for example, equal to or more than 0 km/hour). Further, themicrocomputer 12051 can set a following distance to be maintained infront of a preceding vehicle in advance, and perform automatic brakecontrol (including following stop control), automatic accelerationcontrol (including following start control), or the like. It is thuspossible to perform cooperative control intended for automatic drivingthat makes the vehicle travel autonomously without depending on theoperation of the driver or the like.

For example, the microcomputer 12051 can classify three-dimensionalobject data on three-dimensional objects into three-dimensional objectdata of a two-wheeled vehicle, a standard-sized vehicle, a large-sizedvehicle, a pedestrian, a utility pole, and other three-dimensionalobjects on the basis of the distance information obtained from theimaging sections 12101 to 12104, extract the classifiedthree-dimensional object data, and use the extracted three-dimensionalobject data for automatic avoidance of an obstacle. For example, themicrocomputer 12051 identifies obstacles around the vehicle 12100 asobstacles that the driver of the vehicle 12100 can recognize visuallyand obstacles that are difficult for the driver of the vehicle 12100 torecognize visually. Then, the microcomputer 12051 determines a collisionrisk indicating a risk of collision with each obstacle. In a situationin which the collision risk is equal to or higher than a set value andthere is thus a possibility of collision, the microcomputer 12051outputs a warning to the driver via the audio speaker 12061 or thedisplay section 12062, and performs forced deceleration or avoidancesteering via the driving system control unit 12010. The microcomputer12051 can thereby assist in driving to avoid collision.

At least one of the imaging sections 12101 to 12104 may be an infraredcamera that detects infrared rays. The microcomputer 12051 can, forexample, recognize a pedestrian by determining whether or not there is apedestrian in imaged images of the imaging sections 12101 to 12104. Suchrecognition of a pedestrian is, for example, performed by a procedure ofextracting characteristic points in the imaged images of the imagingsections 12101 to 12104 as infrared cameras and a procedure ofdetermining whether or not it is the pedestrian by performing patternmatching processing on a series of characteristic points representingthe contour of the object. When the microcomputer 12051 determines thatthere is a pedestrian in the imaged images of the imaging sections 12101to 12104, and thus recognizes the pedestrian, the sound/image outputsection 12052 controls the display section 12062 so that a squarecontour line for emphasis is displayed so as to be superimposed on therecognized pedestrian. The sound/image output section 12052 may alsocontrol the display section 12062 so that an icon or the likerepresenting the pedestrian is displayed at a desired position.

8. EXAMPLES Example 1

First, after a glass substrate with an ITO electrode as abottom-electrode was subjected to UV/ozone cleaning, this substrate wasmoved to an organic vapor deposition chamber, and an interior of thechamber was depressurized to 1×10⁻⁵ Pa or lower. Thereafter, while asubstrate holder was rotated, a photoelectric conversion layer includingno halogen atom was formed. Then, an upper inter-layer including ahalogen-containing molecule as a dopant (a guest) was similarly formed.Specifically, in an experiment 1, a naphthalene diimide-based materialexpressed by the following formula (5) was used as a host material, asubphthalocyanine-based material expressed by the following formula (6)was used as a guest material, and a doping concentration (volume %) ofthe guest material was set to 0, 0.01, 0.05, 0.1, 1, 10, and 100(experimental examples 1 to 7). In an experiment 2, the materialexpressed by the formula (5) was used as the host material, asubphthalocyanine-based material expressed by the following formula (7)was used as the guest material, and the doping concentration (volume %)of the guest material was set to 0, 0.01, 0.05, 0.1, 1, 10, and 100(experimental examples 8 to 14). In an experiment 3, the materialexpressed by the formula (5) was used as the host material, ahexaazatriphenylene-based material expressed by the following formula(8) was used as the guest material, and the doping concentration (volume%) of the guest material was set to 0, 0.01, 0.05, 0.1, 1, 10, and 100(experimental examples 15 to 21). Next, after ITO was formed as atop-electrode on the upper inter-layer with use of a sputtering method,a silicon nitride (SiN) film was formed as a protective layer on the ITOwith use of a CVD method.

Tables 1 to 3 are each a summary of the host materials, the guestmaterials, the concentrations (volume %) of the guest materials, filmthicknesses (nm) of the upper inter-layer, and rates (%) of increasing adark current from before to after formation of the protective layer,which were used in the experimental examples 1 to 7, the experimentalexamples 8 to 14, and the experimental examples 15 to 21. FIG. 23 toFIG. 25 each illustrate a relation between the doping concentrations andthe rate (%) of increasing the dark current from before to after theformation of the protective layer in the experiments 1 to 3. In a casewhere the dark current before the formation of the protective layer wasJ_(dk.0) and the dark current after the formation of the protectivelayer was J_(dk), the rate (J_(dk)-J_(dk,0))/J_(dk,0) of increasing thedark current from before to after the formation of the protective layerincreased in a case where the doping concentration was 0.05 volume % orhigher irrespective of the kind of the guest material. This has revealedthat the halogen-containing molecule included in the upper inter-layeris preferably set to less than 0.05 volume % to suppress an increase inthe dark current after the formation of the protective layer.

TABLE 1 Rate of Film Increasing Concentration Thickness Dark CurrentHost Material Guest Material (Volume %) (nm) (%) Experimental Example 1Formula (5) Formula (6) 0 10 0.3 Experimental Example 2 Formula (5)Formula (6) 0.01 10 3 Experimental Example 3 Formula (5) Formula (6)0.05 10 12 Experimental Example 4 Formula (5) Formula (6) 0.1 10 1053Experimental Example 5 Formula (5) Formula (6) 1 10 2248 ExperimentalExample 6 Formula (5) Formula (6) 10 10 6234 Experimental Example 7Formula (5) Formula (6) 100 10 10543

TABLE 2 Rate of Film Increasing Concentration Thickness Dark CurrentHost Material Guest Material (Volume %) (nm) (%) Experimental Example 8 Formula (5) Formula (7) 0 10 0.23 Experimental Example 9  Formula (5)Formula (7) 0.01 10 2.3 Experimental Example 10 Formula (5) Formula (7)0.05 10 8 Experimental Example 11 Formula (5) Formula (7) 0.1 10 13Experimental Example 12 Formula (5) Formula (7) 1 10 322 ExperimentalExample 13 Formula (5) Formula (7) 10 10 237 Experimental Example 14Formula (5) Formula (7) 100 10 534

3TABLE 3 Rate of Film Increasing Concentration Thickness Dark CurrentHost Material Guest Material (Volume %) (nm) (%) Experimental Example 15Formula (5) Formula (8) 0 10 0.9 Experimental Example 16 Formula (5)Formula (8) 0.01 10 1.2 Experimental Example 17 Formula (5) Formula (8)0.05 10 2 Experimental Example 18 Formula (5) Formula (8) 0.1 10 13Experimental Example 19 Formula (5) Formula (8) 1 10 322 ExperimentalExample 20 Formula (5) Formula (8) 10 10 592 Experimental Example 21Formula (5) Formula (8) 100 10 848

Example 2

First, after a glass substrate with an ITO electrode as abottom-electrode was subjected to UV/ozone cleaning, this substrate wasmoved to an organic vapor deposition chamber, and an interior of thechamber was depressurized to 1×10⁻⁵ Pa or lower. Thereafter, while asubstrate holder was rotated, as a photoelectric conversion layer, filmsof an electron donor material, an electron acceptor material, and a dyematerial were formed by means of vacuum co-evaporation to have a filmthickness ratio of 4:2:4 and a total film thickness of 230 nm. Then,after an upper inter-layer containing no halogen atom was formed bymeans of vacuum deposition, similarly to Example 1, a top-electrode anda protective layer were formed in order. In this example, as the dyematerial, a subphthalocyanine-based material expressed by the followingformula (9) (an experimental example 22), the material expressed by theformula (6) (an experimental example 23), a subphthalocyanine-basedmaterial expressed by the following formula (10) (an experimentalexample 24), the material expressed by the formula (7) (an experimentalexample 25), a subphthalocyanine-based material expressed by thefollowing formula (11) (an experimental example 26), and asubphthalocyanine-based material expressed by the following formula (12)(an experimental example 27) were used. The same material was used forthe electron donor material, the electron acceptor material, and theupper inter-layer.

Table 4 is a summary of the dye materials, the materials of the upperinter-layer, minimum binding energy (eV) of a halogen atom in a moleculeof the dye material, and the rate (%) of increasing the dark currentfrom before to after the formation of the protective layer, each ofwhich was used in the experimental examples 22 to 27. FIG. 26illustrates a relation between the minimum binding energy and the rateof increasing the dark current from before to after the formation of theprotective layer. From an examination of dependence of the rate (%) ofincreasing the dark current from before to after the formation of theprotective layer on the dye material, a correlation was observed betweenthe minimum binding energy of the halogen atom and the rate ofincreasing the dark current in binding having a halogen contained in themolecule of the dye material. This has revealed that in a case where thehalogen-containing molecule is present in the photoelectric conversionlayer and the minimum binding energy of the binding having the halogenatom is 5.4 eV or higher, an increase in the dark current after theformation of the protective layer is suppressed. It is to be noted thatbinding disassociation energy was computed by calculation of an energychange in reaction expressed by the following formula (1). A densityfunctional theory was used as a calculation method. B3LYP was used for afunctional and 6-31G** was used for a basis function.

[Math. 1]

AB→A·+B·  (1)

TABLE 4 Minimum Rate Binding of Increasing Upper Energy Dark Current DyeMaterial Inter-layer (eV) (%) Experimental Formula (9)  Formula (5) 4.544536 Example 22 Experimental Formula (6)  Formula (5) 4.93 832 Example23 Experimental Formula (10) Formula (5) 4.95 2454 Example 24Experimental Formula (7)  Formula (5) 5.37 53 Example 25 ExperimentalFormula (11) Formula (5) 5.5 33 Example 26 Experimental Formula (12)Formula (5) 7.15 60 Example 27

Example 3

First, after a glass substrate with an ITO electrode as abottom-electrode was subjected to UV/ozone cleaning, this substrate wasmoved to an organic vapor deposition chamber and an interior of thechamber was depressurized to 1×10⁻⁵ Pa or lower. Thereafter, while thesubstrate holder was rotated, as a photoelectric conversion layer, filmsof an electron donor material, an electron acceptor material, and a dyematerial were formed by means of vacuum co-evaporation to have a filmthickness ratio of 4:2:4 and a total film thickness of 230 nm. Then,after an upper inter-layer containing no halogen atom was formed bymeans of vacuum deposition, similarly to Example 1, a top-electrode anda protective layer were formed in order. In this example, as a materialof the upper inter-layer, the material expressed by the formula (5) (anexperimental example 28), a naphthalene diimide-based material expressedby the following formula (13) (an experimental example 29), anaphthalene diimide-based material expressed by the following formula(14) (an experimental example 30), a naphthalene diimide-based materialexpressed by the following formula (15) (an experimental example 31), anaphthalene-1,4,5,8-tetracarboxylic dianhydride (an experimental example32), a naphthalene diimide-based material expressed by the followingformula (17) (an experimental example 33), molybdenum oxide (MoO₃) (anexperimental example 34), tungsten oxide (WO₃) (an experimental example35), a hexaazatriphenylene-based material expressed by the followingformula (18) (an experimental example 36), and the material expressed bythe formula (5) (an experimental example 37) were used. The samematerial was used for the electron donor material, the electron acceptormaterial, and the upper inter-layer.

Table 5 is a summary of work functions of the top-electrodes in theexperimental examples 28 to 37, electron affinity (eV) of the upperinter-layer and the photoelectric conversion layer, relative values ofthe dark current, and relative values of quantum efficiency, each ofwhich is in the experimental examples 28 to 37. FIG. 27 illustrates arelation of the electron affinity of the upper inter-layer and the darkcurrent in the experimental examples 28 to 33. FIG. 28 illustrates arelation of the electron affinity of the upper inter-layer and thequantum efficiency in the experimental examples 28 to 33. FIG. 29illustrates a relation of the electron affinity of the upper inter-layerand the dark current in the experimental examples 34 to 37. FIG. 30illustrates a relation of the electron affinity of the upper inter-layerand the quantum efficiency in the experimental examples 34 to 37.

In this example, dependence of the upper inter-layer on the dark currentrelative value after the formation of the protective layer and thequantum efficiency relative value was examined. It is to be noted thatthe quantum efficiency was evaluated by application of green lighthaving an excitation wavelength of 560 nm and intensity of 10 μW/cm².The work function of the top-electrode was acquired with use of anultraviolet photoelectron spectroscopy method. The electron affinity ofeach of the materials of the upper inter-layer and the photoelectricconversion layer was computed through subtracting an ionizationpotential obtained by the ultraviolet photoelectron spectroscopy methodand an optical bandgap obtained by absorption spectroscopy measurement.As a result, it has been revealed that it is possible to establish botha low dark current and high quantum efficiency in a case where thetop-electrode is a cathode and the upper inter-layer that satisfiesEA2≤EA1≤WF is used where the work function of the top-electrode is WF,the electron affmity of the upper inter-layer is EA1, and electronaffinity of a material having the smallest electron affinity of thephotoelectric conversion materials is EA2. In addition, it has beenrevealed that in a case where the top-electrode is an anode, it ispossible to establish both a low dark current and high quantumefficiency in a case where EA1>WF.

TABLE 5 Electron Affinity of Photoelectric Conversion Upper Inter-layerLayer Material (eV) Dark Quantum Top-electrode Electron ElectronElectron Current Efficiency Work Affinity Donor Dye Acceptor RelativeRelative Material Polarity Function Material (eV) Material MaterialMaterial Value Value Experimental Example 28 ITO Cathode 4.8 Formula (5)4.8 2.5 4.5 4.5 1 1 Experimental Example 29 ITO Cathode 4.8 Formula (13)4.3 2.5 4.5 4.5 1.29 0.71 Experimental Example 30 ITO Cathode 4.8Formula (14) 4.7 23 4.5 4.5 1.36 1.01 Experimental Example 31 ITOCathode 4.8 Formula (15) 5.4 2.5 4.5 4.5 11.3 0.99 Experimental Example32 ITO Cathode 4.8 Formula (16) 4.9 2.5 4.5 4.5 3.78 1 ExperimentalExample 33 ITO Cathode 4.8 Formula (17) 4.5 2.5 4.5 4.5 0.95 0.98Experimental Example 34 ITO Anode 4.8 MoO₃ 6.7 2.5 4.5 4.5 1 1Experimental Example 35 ITO Anode 4.8 WO₃ 6.5 2.5 4.5 4.5 1 1.02Experimental Example 36 ITO Anode 4.8 Formula (18) 5.6 2.5 4.5 4.5 1.190.99 Experimental Example 37 ITO Anode 4.8 Formula (5) 4.8 2.5 4.5 4.521 0.7

Example 4

First, after a glass substrate with an ITO electrode as abottom-electrode was subjected to UV/ozone cleaning, this substrate wasmoved to an organic vapor deposition chamber and an interior of thechamber was depressurized to 1×10⁻⁵ Pa or lower. Thereafter, while asubstrate holder was rotated, as a photoelectric conversion layer, filmsof an electron donor material, an electron acceptor material, and a dyematerial having a halogen atom in a molecule were formed by means ofvacuum co-evaporation to have a film thickness ratio of 4:2:4 and atotal film thickness of 230 nm. Then, an upper inter-layer containing nohalogen atom was formed by means of vacuum deposition. At that time, afilm thickness of the upper inter-layer was set to 3 nm (an experimentalexample 38), 5 nm (an experimental example 39), 7 nm (an experimentalexample 40), 10 nm (an experimental example 41), 15 nm (an experimentalexample 42), and 20 nm (an experimental example 43). Thereafter,similarly to Example 1, a top-electrode and a protective layer wereformed in order. In this example, the material expressed by the formula(7) was used as the dye material, and the material expressed by theformula (5) was used as the upper inter-layer. In addition, in all theexperimental examples, the same material was used for the electron donormaterial and the electron acceptor material.

Table 6 is a summary of the dye material, the material of the upperinter-layer, the film thickness (nm) of the upper inter-layer, and therate (%) of increasing the dark current from before to after theformation of the protective layer, each of which is in the experimentalexamples 34 to 43. FIG. 31 illustrates the film thickness of the upperinter-layer, that is, a relation of a distance between the photoelectricconversion layer and the top-electrode and the rate(J_(dk)-J_(dk,0))/J_(dk,0) of increasing the dark current from before toafter the formation of the protective layer. It has been revealed fromthe result of Example 2 that even though no halogen-containing moleculeis included in the upper inter-layer, desorption of the halogen atomoccurs to no small extent during formation of the top-electrode or theprotective layer, in a case where the halogen-containing molecule isincluded in the photoelectric conversion layer, which thus results in anincrease in dark current. This is assumed to be attributable topenetration, into the photoelectric conversion layer, of ultravioletrays generated upon formation of the top-electrode or the protectivelayer, for example.

TABLE 6 Rate Film of Increasing Upper Thickness Dark Current DyeMaterial Inter-layer (nm) (%) Experimental Formula (7) Formula (5) 3 847Example 38 Experimental Formula (7) Formula (5) 5 1 Example 39Experimental Formula (7) Formula (5) 7 0.8 Example 40 ExperimentalFormula (7) Formula (5) 10 0.3 Example 41 Experimental Formula (7)Formula (5) 15 1 Example 42 Experimental Formula (7) Formula (5) 20 0.8Example 43

An examination of the dependence, on the film thickness of the upperinter-layer, of the rate of increasing the dark current from before toafter the formation of the protective layer has revealed that theincrease in the dark current after the formation of the protective layeris suppressed through making the film thickness 5 nm or larger, that is,making the distance from the top-electrode to the photoelectricconversion layer including the halogen-containing molecule 5 nm orlarger.

Although the description has been given with reference to the foregoingfirst and sixth embodiments, the application examples, and the examples,the content of the present disclosure is not limited to the foregoingembodiments, etc., and may be modified in a variety of ways. Forexample, although the photoelectric conversion element in the foregoingfirst embodiment has a configuration in which the organic photoelectricconverter 20 detecting the green light and the inorganic photoelectricconverters 32B and 32R respectively detecting blue light and red lightare stacked, the contents of the present disclosure are not limited tosuch a configuration. That is, the organic photoelectric converter maydetect red light or blue light, and the inorganic photoelectricconverter may detect green light.

In addition, the number of organic photoelectric converters, the numberof inorganic photoelectric converters, a ratio between the organicphotoelectric converters and the inorganic photoelectric converters arenot limited, and two or more organic photoelectric converters may beprovided, or color signals of a plurality of colors may be obtained byonly the organic photoelectric converter. Further, the content of thepresent disclosure is not limited to a configuration in which organicphotoelectric converters and inorganic photoelectric converters arestacked in the longitudinal direction, and organic photoelectricconverters and inorganic photoelectric converters may be disposed sideby side along a substrate surface.

Furthermore, in the foregoing first embodiment, the configuration of theback-side illumination type solid-state imaging apparatus has beenexemplified: however, the contents of the present disclosure areapplicable to a front-side illumination type solid-state imagingapparatus. In addition, it is not necessary that the solid-state imagingelement (and the imaging apparatus) of the present disclosure includeall of the respective components described in the foregoing embodiments,and or may include any other layer.

It is to be noted that the effects described herein are merelyillustrative and non-limiting, and other effects may be included.

Moreover, the present disclosure may have the following configurations.

-   (1)

A solid-state imaging element including:

a bottom-electrode;

a top-electrode opposed to the bottom-electrode;

a photoelectric conversion layer provided between the bottom-electrodeand the top-electrode and including a first organic semiconductormaterial; and

an upper inter-layer provided between the top-electrode and thephotoelectric conversion layer, and including a second organicsemiconductor material having a halogen atom in a molecule at aconcentration in a range from 0 volume % or more to less than 0.05volume %.

-   (2)

The solid-state imaging element according to (1), in which the firstorganic semiconductor material includes one or two or more halogen atomsin the molecule, and binding energy of a halogen atom having smallestbinding energy in the molecule is 5.4 eV or higher.

-   (3)

The solid-state imaging element according to (1) or (2), in which thephotoelectric conversion layer includes a third organic semiconductormaterial or a fourth organic semiconductor material or both, the thirdorganic semiconductor material serving as an electron donor to the firstorganic semiconductor material and the fourth organic semiconductormaterial serving as an electron acceptor to the first organicsemiconductor material.

-   (4)

The solid-state imaging element according to any of (1) to (3), in whichthe first organic semiconductor material is a boronatedsubphthalocyanine derivative.

-   (5)

The solid-state imaging element according to any of (2) to (4), in whichin a case where the top-electrode functions as a cathode, a workfunction (WF) of the top-electrode, electron affinity of the upperinter-layer (EA1), and electron affinity of a material having smallestelectron affinity of materials included in the photoelectric conversionlayer (EA2) satisfy EA2≤EA1≤WF.

-   (6)

The solid-state imaging element according to any of (2) or (5), in whichin a case where the top-electrode functions as an anode, the workfunction (WF) of the top-electrode and the electron affinity of theupper inter-layer (EA1) satisfy EA1>WF.

-   (7)

The solid-state imaging element according to any of (1) to (6), in whicha distance between the top-electrode and the photoelectric conversionlayer is in a range from 5 nm to 20 nm both inclusive.

-   (8)

The solid-state imaging element according to any of (1) to (7), in whichthe top-electrode is formed including one or more kinds of indium tinoxide (ITO), indium zinc oxide (IZO), and indium-tungsten oxide (IWO).

-   (9)

The solid-state imaging element according to any of (1) to (8), in whichan organic photoelectric converter including one or a plurality of thephotoelectric conversion layers, and one or a plurality of inorganicphotoelectric converters are stacked, the inorganic photoelectricconverters performing photoelectric conversion in a different wavelengthrange from the organic photoelectric converter.

-   (10)

The solid-state imaging element according to any of (9), in which

the inorganic photoelectric converter is formed to be embedded in asemiconductor substrate, and

the organic photoelectric converter is formed on a side on which a firstsurface is located of the semiconductor substrate.

-   (11)

A solid-state imaging element including:

a bottom-electrode;

a top-electrode opposed to the bottom-electrode;

a photoelectric conversion layer provided between the bottom-electrodeand the top-electrode and including an organic semiconductor materialthat has one or two or more halogen atoms in a molecule and in whichbinding energy of a halogen atom having smallest binding energy in themolecule is 5.4 eV or higher; and

an upper inter-layer provided between the top-electrode and thephotoelectric conversion layer.

-   (12)

A solid-state imaging element including:

a bottom-electrode;

a top-electrode opposed to the bottom-electrode;

a photoelectric conversion layer provided between the bottom-electrodeand the top-electrode and including an organic semiconductor materialhaving a halogen atom in a molecule; and

an organic semiconductor layer provided between the top-electrode andthe photoelectric conversion layer, wherein

a distance between the top-electrode and the photoelectric conversionlayer is in a range from 5 nm to 20 nm both inclusive.

-   (13)

A solid-state imaging element including:

a first electrode;

a second electrode opposed to the first electrode; and

a photoelectric conversion layer provided between the first electrodeand the second electrode, in which

the photoelectric conversion layer includes an exciton generation layerincluding a dye material and a first semiconductor material, and anexciton disassociation layer including a second semiconductor material.

-   (14)

The solid-state imaging element according to (13), in which thephotoelectric conversion layer includes a first inter-layer including afirst semiconductor material between the exciton generation layer andthe exciton disassociation layer.

-   (15)

The solid-state imaging element according to (14), in which thephotoelectric conversion layer includes a second inter-layer includingthe first semiconductor material and the second semiconductor materialbetween the first inter-layer and the exciton disassociation layer.

-   (16)

The solid-state imaging element according to any of (13) to (15), inwhich the first semiconductor material and the second semiconductormaterial are semiconductor materials having mutually differentpolarities.

-   (17)

The solid-state imaging element according to any of (13) to (16), inwhich a bandgap of the first semiconductor material is equal to abandgap of the dye material or smaller than the bandgap of the dyematerial.

-   (18)

The solid-state imaging element according to any of (13) to (17), inwhich the first semiconductor material and the second semiconductormaterial have a difference in energy level.

-   (19)

The solid-state imaging element according to any of (13) to (18), inwhich the second semiconductor material forms an interface with thefirst semiconductor material and is not in direct contact with the dyematerial.

-   (20)

The solid-state imaging element according to any of (13) to (19), inwhich the dye material, the first semiconductor material, and the secondsemiconductor material are organic materials.

-   (21)

A solid-state imaging apparatus provided with a plurality of pixels eachincluding one or a plurality of solid-state imaging elements, each ofthe solid-state imaging elements including:

a bottom-electrode;

a top-electrode opposed to the bottom-electrode;

a photoelectric conversion layer provided between the bottom-electrodeand the top-electrode and including a first organic semiconductormaterial; and

an upper inter-layer provided between the top-electrode and thephotoelectric conversion layer, and including a second organicsemiconductor material having a halogen atom in a molecule at aconcentration in a range from 0 volume % or more to less than 0.05volume %.

-   (22)

A solid-state imaging apparatus provided with a plurality of pixels eachincluding one or a plurality of solid-state imaging elements, each ofthe solid-state imaging elements including:

a bottom-electrode; and

a top-electrode opposed to the bottom-electrode;

a photoelectric conversion layer provided between the bottom-electrodeand the top-electrode and including an organic semiconductor materialthat has one or two or more halogen atoms in a molecule and in whichbinding energy of a halogen atom having smallest binding energy in themolecule is 5.4 eV or higher; and

an upper inter-layer provided between the top-electrode and thephotoelectric conversion layer.

-   (23)

A solid-state imaging apparatus provided with a plurality of pixels eachincluding one or a plurality of solid-state imaging elements, each ofthe solid-state imaging elements comprising:

a bottom-electrode;

a top-electrode opposed to the bottom-electrode;

a photoelectric conversion layer provided between the bottom-electrodeand the top-electrode and including an organic semiconductor materialhaving a halogen atom in a molecule; and

an organic semiconductor layer provided between the top-electrode andthe photoelectric conversion layer, in which

a distance between the top-electrode and the photoelectric conversionlayer is in a range from 5 nm to 20 nm both inclusive.

-   (24)

A solid-state imaging apparatus provided with a plurality of pixels eachincluding one or a plurality of solid-state imaging elements, each ofthe solid-state imaging elements comprising:

a first electrode;

a second electrode opposed to the first electrode; and

a photoelectric conversion layer provided between the first electrodeand the second electrode, wherein

the photoelectric conversion layer includes an exciton generation layerincluding a dye material and a first semiconductor material, and anexciton disassociation layer including a second semiconductor material.

This application claims the benefits of Japanese Priority PatentApplication No. 2016-142154 filed on Jul. 20, 2016 and Japanese PriorityPatent Application No. 2016-155728 filed on Aug. 8, 2016, the entirecontents of which are incorporated herein by reference.

It should be understood that those skilled in the art could conceivevarious modifications, combinations, sub-combinations, and alterationsdepending on design requirements and other factors, insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is: 1.-24. (canceled)
 25. A solid-state imaging elementcomprising: a bottom-electrode; a top-electrode opposed to thebottom-electrode; a photoelectric conversion layer provided between thebottom-electrode and the top-electrode and including an organicsemiconductor material that has one or two or more halogen atoms in amolecule and in which binding energy of a halogen atom having smallestbinding energy in the molecule is 5.4 eV or higher; and an upperinter-layer provided between the top-electrode and the photoelectricconversion layer.
 26. The solid-state imaging element of claim 25,wherein the first organic semiconductor material is selected from thegroup consisting of a quinacridone derivative, boronatedsubphthalocyanine derivative, pentacene derivative, fullerenederivative, benzothieno-benzothiphene derivative, and combinationsthereof.
 27. The solid-state imaging element of claim 26, wherein thefirst organic semiconductor material is the boronated subphthalocyaninederivative.
 28. The solid-state imaging element of claim 27, wherein thefirst organic semiconductor material is boron subphthalocyaninechloride.
 29. The solid-state imaging element of claim 25, wherein thephotoelectric conversion layer includes a third organic semiconductormaterial or a fourth organic semiconductor material or both, the thirdorganic semiconductor material serving as an electron donor to the firstorganic semiconductor material and the fourth organic semiconductormaterial serving as an electron acceptor to the first organicsemiconductor material.
 30. The solid-state imaging element of claim 25,wherein the upper inter-layer comprises a second organic semiconductormaterial having a halogen atom in a molecule, wherein a concentration ofthe second organic semiconductor material is less than 0.05 volume % ofthe upper inter-layer.
 31. The solid-state imaging element of claim 25,wherein in a case where the top-electrode functions as a cathode, a workfunction (WF) of the top-electrode, an electron affinity of the upperinter-layer (EA1), and an electron affinity of a material havingsmallest electron affinity of materials included in the photoelectricconversion layer (EA2) satisfy EA2≤EA1≤WF.
 32. The solid-state imagingelement of claim 25, wherein in a case where the top-electrode functionsas an anode, the work function (WF) of the top-electrode and theelectron affinity of the upper inter-layer (EA1) satisfy EA1>WF.
 33. Thesolid-state imaging element of claim 25, wherein the top-electrode isformed from a material comprising indium tin oxide (ITO), indium zincoxide (IZO), and indium-tungsten oxide (IWO).
 34. The solid-stateimaging element of claim 25, wherein an organic photoelectric converterincluding one or a plurality of the photoelectric conversion layers, andone or a plurality of inorganic photoelectric converters are stacked,the inorganic photoelectric converters performing photoelectricconversion in a different wavelength range from the organicphotoelectric converter.
 35. A solid-state imaging apparatus providedwith a plurality of pixels each including one or a plurality ofsolid-state imaging elements, each of the solid-state imaging elementscomprising: a bottom-electrode; and a top-electrode opposed to thebottom-electrode; a photoelectric conversion layer provided between thebottom-electrode and the top-electrode and including an organicsemiconductor material that has one or two or more halogen atoms in amolecule and in which binding energy of a halogen atom having smallestbinding energy in the molecule is 5.4 eV or higher; and an upperinter-layer provided between the top-electrode and the photoelectricconversion layer.